Last Updated on December 13, 2021 by Admin 3

CISA : Certified Information Systems Auditor : Part 67

  1. Which of the following type of network service is used by network computer to obtain an IP addresses and other parameters such as default gateway, subnet mask?

    • DHCP
    • DNS
    • Directory Service
    • Network Management

    Explanation:

    Dynamic Host Configuration Protocol (DHCP) – The Dynamic Host Configuration Protocol (DHCP) is a standardized networking protocol used on Internet Protocol (IP) networks for dynamically distributing network configuration parameters, such as IP addresses for interfaces and services. With DHCP, computers request IP addresses and networking parameters automatically from a DHCP server, reducing the need for a network administrator or a user to configure these settings manually.

    For your exam you should know below information about network services:

    In computer networking, a network service is an application running at the network application layer and above, that provides data storage, manipulation, presentation, communication or other capability which is often implemented using a client-server or peer-to-peer architecture based on application layer network protocols.
    Each service is usually provided by a server component running on one or more computers (often a dedicated server computer offering multiple services) and accessed via a network by client components running on other devices. However, the client and server components can both be run on the same machine.
    Clients and servers will often have a user interface, and sometimes other hardware associated with them.

    Different types of network services are as follows:
    Network File System – Network File System (NFS) is a distributed file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a network much like local storage is accessed.
    Remote Access Service – Remote Access Services (RAS) refers to any combination of hardware and software to enable the remote access tools or information that typically reside on a network of IT devices.
    Directory Services – A directory service is the software system that stores, organizes and provides access to information in a directory. In software engineering, a directory is a map between names and values. It allows the lookup of values given a name, similar to a dictionary. As a word in a dictionary may have multiple definitions, in a directory, a name may be associated with multiple, different pieces of information. Likewise, as a word may have different parts of speech and different definitions, a name in a directory may have many different types of data.
    Network Management – In computer networks, network management refers to the activities, methods, procedures, and tools that pertain to the operation, administration, maintenance, and provisioning of networked systems. Network management is essential to command and control practices and is generally carried out of a network operations center.
    Dynamic Host Configuration Protocol (DHCP) – The Dynamic Host Configuration Protocol (DHCP) is a standardized networking protocol used on Internet Protocol (IP) networks for dynamically distributing network configuration parameters, such as IP addresses for interfaces and services. With DHCP, computers request IP addresses and networking parameters automatically from a DHCP server, reducing the need for a network administrator or a user to configure these settings manually.
    Email service – Provides the ability, through a terminal or PC connected to a communication network, to send an entrusted message to another individual or group of people.
    Print Services – Provide the ability, typically through a print server on a network, to manage and execute print request services from other devices on the network
    Domain Name System(DNS) – Translates the names of network nodes into network IP address.

    The following were incorrect answers:
    Directory Service – A directory service is the software system that stores, organizes and provides access to information in a directory. In software engineering, a directory is a map between names and values. It allows the lookup of values given a name, similar to a dictionary. As a word in a dictionary may have multiple definitions, in a directory, a name may be associated with multiple, different pieces of information. Likewise, as a word may have different parts of speech and different definitions, a name in a directory may have many different types of data.
    Domain Name System(DNS) – Translates the names of network nodes into network IP address.
    Network Management – In computer networks, network management refers to the activities, methods, procedures, and tools that pertain to the operation, administration, maintenance, and provisioning of networked systems. Network management is essential to command and control practices and is generally carried out of a network operations center.

    Reference:

    CISA review manual 2014 Page number 258

  2. Which of the following layer of the OSI model provides a standard interface for applications to communicate with devices on a network?

    • Application layer
    • Presentation layer
    • Session layer
    • Transport layer
    Explanation:

    The application layer serves as the window for users and application processes to access network services. This layer contains a variety of commonly needed functions:

    Resource sharing and device redirection
    Remote file access
    Remote printer access
    Inter-process communication
    Network management
    Directory services
    Electronic messaging (such as mail)
    Network virtual terminals

    For your exam you should know below information about OSI model:

    The Open Systems Interconnection model (OSI) is a conceptual model that characterizes and standardizes the internal functions of a communication system by partitioning it into abstraction layers. The model is a product of the Open Systems Interconnection project at the International Organization for Standardization (ISO), maintained by the identification ISO/IEC 7498-1.

    The model groups communication functions into seven logical layers. A layer serves the layer above it and is served by the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of that path. Two instances at one layer are connected by a horizontal.
    OSI Model

    CISA Certified Information Systems Auditor Part 67 Q02 071
    CISA Certified Information Systems Auditor Part 67 Q02 071

    PHYSICAL LAYER
    The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. It describes the electrical/optical, mechanical, and functional interfaces to the physical medium, and carries the signals for all of the higher layers. It provides:

    Data encoding: modifies the simple digital signal pattern (1s and 0s) used by the PC to better accommodate the characteristics of the physical medium, and to aid in bit and frame synchronization. It determines:
    What signal state represents a binary 1
    How the receiving station knows when a “bit-time” starts
    How the receiving station delimits a frame

    DATA LINK LAYER
    The data link layer provides error-free transfer of data frames from one node to another over the physical layer, allowing layers above it to assume virtually error-free transmission over the link. To do this, the data link layer provides:

    Link establishment and termination: establishes and terminates the logical link between two nodes.
    Frame traffic control: tells the transmitting node to “back-off” when no frame buffers are available.
    Frame sequencing: transmits/receives frames sequentially.
    Frame acknowledgment: provides/expects frame acknowledgments. Detects and recovers from errors that occur in the physical layer by retransmitting non-acknowledged frames and handling duplicate frame receipt.
    Frame delimiting: creates and recognizes frame boundaries.
    Frame error checking: checks received frames for integrity.
    Media access management: determines when the node “has the right” to use the physical medium.

    NETWORK LAYER
    The network layer controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service, and other factors. It provides:
    Routing: routes frames among networks.
    Subnet traffic control: routers (network layer intermediate systems) can instruct a sending station to “throttle back” its frame transmission when the router’s buffer fills up.
    Frame fragmentation: if it determines that a downstream router’s maximum transmission unit (MTU) size is less than the frame size, a router can fragment a frame for transmission and re-assembly at the destination station.
    Logical-physical address mapping: translates logical addresses, or names, into physical addresses.
    Subnet usage accounting: has accounting functions to keep track of frames forwarded by subnet intermediate systems, to produce billing information.

    Communications Subnet
    The network layer software must build headers so that the network layer software residing in the subnet intermediate systems can recognize them and use them to route data to the destination address.

    This layer relieves the upper layers of the need to know anything about the data transmission and intermediate switching technologies used to connect systems. It establishes, maintains and terminates connections across the intervening communications facility (one or several intermediate systems in the communication subnet).

    In the network layer and the layers below, peer protocols exist between a node and its immediate neighbor, but the neighbor may be a node through which data is routed, not the destination station. The source and destination stations may be separated by many intermediate systems.

    TRANSPORT LAYER
    The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.

    The size and complexity of a transport protocol depends on the type of service it can get from the network layer. For a reliable network layer with virtual circuit capability, a minimal transport layer is required. If the network layer is unreliable and/or only supports datagram’s, the transport protocol should include extensive error detection and recovery.

    The transport layer provides:
    Message segmentation: accepts a message from the (session) layer above it, splits the message into smaller units (if not already small enough), and passes the smaller units down to the network layer. The transport layer at the destination station reassembles the message.
    Message acknowledgment: provides reliable end-to-end message delivery with acknowledgments.
    Message traffic control: tells the transmitting station to “back-off” when no message buffers are available.
    Session multiplexing: multiplexes several message streams, or sessions onto one logical link and keeps track of which messages belong to which sessions (see session layer).

    Typically, the transport layer can accept relatively large messages, but there are strict message size limits imposed by the network (or lower) layer. Consequently, the transport layer must break up the messages into smaller units, or frames, pretending a header to each frame.

    The transport layer header information must then include control information, such as message start and message end flags, to enable the transport layer on the other end to recognize message boundaries. In addition, if the lower layers do not maintain sequence, the transport header must contain sequence information to enable the transport layer on the receiving end to get the pieces back together in the right order before handing the received message up to the layer above.

    End-to-end layers
    Unlike the lower “subnet” layers whose protocol is between immediately adjacent nodes, the transport layer and the layers above are true “source to destination” or end-to-end layers, and are not concerned with the details of the underlying communications facility. Transport layer software (and software above it) on the source station carries on a conversation with similar software on the destination station by using message headers and control messages.

    SESSION LAYER
    The session layer allows session establishment between processes running on different stations. It provides:
    Session establishment, maintenance and termination: allows two application processes on different machines to establish, use and terminate a connection, called a session.
    Session support: performs the functions that allow these processes to communicate over the network, performing security, name recognition, logging, and so on.

    PRESENTATION LAYER
    The presentation layer formats the data to be presented to the application layer. It can be viewed as the translator for the network. This layer may translate data from a format used by the application layer into a common format at the sending station, then translate the common format to a format known to the application layer at the receiving station.

    The presentation layer provides:
    Character code translation: for example, ASCII to EBCDIC.
    Data conversion: bit order, CR-CR/LF, integer-floating point, and so on.
    Data compression: reduces the number of bits that need to be transmitted on the network.
    Data encryption: encrypt data for security purposes. For example, password encryption.

    APPLICATION LAYER
    The application layer serves as the window for users and application processes to access network services. This layer contains a variety of commonly needed functions:
    Resource sharing and device redirection
    Remote file access
    Remote printer access
    Inter-process communication
    Network management
    Directory services
    Electronic messaging (such as mail)
    Network virtual terminals

    The following were incorrect answers:
    Presentation layer – The presentation layer formats the data to be presented to the application layer. It can be viewed as the translator for the network. This layer may translate data from a format used by the application layer into a common format at the sending station, then translate the common format to a format known to the application layer at the receiving station.

    Session layer – The session layer allows session establishment between processes running on different stations.

    Transport layer – The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.

    Reference:

    CISA review manual 2014 Page number 260

  3. Which of the following layer of an OSI model controls dialog between computers?

    • Application layer
    • Presentation layer
    • Session layer
    • Transport layer
    Explanation:

    The session layer allows session establishment between processes running on different stations. It provides:
    Session establishment, maintenance and termination: allows two application processes on different machines to establish, use and terminate a connection, called a session.
    Session support: performs the functions that allow these processes to communicate over the network, performing security, name recognition, logging, and so on.

    For your exam you should know below information about OSI model:

    The Open Systems Interconnection model (OSI) is a conceptual model that characterizes and standardizes the internal functions of a communication system by partitioning it into abstraction layers. The model is a product of the Open Systems Interconnection project at the International Organization for Standardization (ISO), maintained by the identification ISO/IEC 7498-1.

    The model groups communication functions into seven logical layers. A layer serves the layer above it and is served by the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of that path. Two instances at one layer are connected by a horizontal.
    OSI Model

    CISA Certified Information Systems Auditor Part 67 Q03 073
    CISA Certified Information Systems Auditor Part 67 Q03 073

    PHYSICAL LAYER
    The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. It describes the electrical/optical, mechanical, and functional interfaces to the physical medium, and carries the signals for all of the higher layers. It provides:

    Data encoding: modifies the simple digital signal pattern (1s and 0s) used by the PC to better accommodate the characteristics of the physical medium, and to aid in bit and frame synchronization. It determines:
    What signal state represents a binary 1
    How the receiving station knows when a “bit-time” starts
    How the receiving station delimits a frame

    DATA LINK LAYER
    The data link layer provides error-free transfer of data frames from one node to another over the physical layer, allowing layers above it to assume virtually error-free transmission over the link. To do this, the data link layer provides:

    Link establishment and termination: establishes and terminates the logical link between two nodes.
    Frame traffic control: tells the transmitting node to “back-off” when no frame buffers are available.
    Frame sequencing: transmits/receives frames sequentially.
    Frame acknowledgment: provides/expects frame acknowledgments. Detects and recovers from errors that occur in the physical layer by retransmitting non-acknowledged frames and handling duplicate frame receipt.
    Frame delimiting: creates and recognizes frame boundaries.
    Frame error checking: checks received frames for integrity.
    Media access management: determines when the node “has the right” to use the physical medium.

    NETWORK LAYER
    The network layer controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service, and other factors. It provides:
    Routing: routes frames among networks.
    Subnet traffic control: routers (network layer intermediate systems) can instruct a sending station to “throttle back” its frame transmission when the router’s buffer fills up.
    Frame fragmentation: if it determines that a downstream router’s maximum transmission unit (MTU) size is less than the frame size, a router can fragment a frame for transmission and re-assembly at the destination station.
    Logical-physical address mapping: translates logical addresses, or names, into physical addresses.
    Subnet usage accounting: has accounting functions to keep track of frames forwarded by subnet intermediate systems, to produce billing information.

    Communications Subnet
    The network layer software must build headers so that the network layer software residing in the subnet intermediate systems can recognize them and use them to route data to the destination address.

    This layer relieves the upper layers of the need to know anything about the data transmission and intermediate switching technologies used to connect systems. It establishes, maintains and terminates connections across the intervening communications facility (one or several intermediate systems in the communication subnet).

    In the network layer and the layers below, peer protocols exist between a node and its immediate neighbor, but the neighbor may be a node through which data is routed, not the destination station. The source and destination stations may be separated by many intermediate systems.

    TRANSPORT LAYER
    The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.

    The size and complexity of a transport protocol depends on the type of service it can get from the network layer. For a reliable network layer with virtual circuit capability, a minimal transport layer is required. If the network layer is unreliable and/or only supports datagram’s, the transport protocol should include extensive error detection and recovery.

    The transport layer provides:
    Message segmentation: accepts a message from the (session) layer above it, splits the message into smaller units (if not already small enough), and passes the smaller units down to the network layer. The transport layer at the destination station reassembles the message.
    Message acknowledgment: provides reliable end-to-end message delivery with acknowledgments.
    Message traffic control: tells the transmitting station to “back-off” when no message buffers are available.
    Session multiplexing: multiplexes several message streams, or sessions onto one logical link and keeps track of which messages belong to which sessions (see session layer).

    Typically, the transport layer can accept relatively large messages, but there are strict message size limits imposed by the network (or lower) layer. Consequently, the transport layer must break up the messages into smaller units, or frames, pretending a header to each frame.

    The transport layer header information must then include control information, such as message start and message end flags, to enable the transport layer on the other end to recognize message boundaries. In addition, if the lower layers do not maintain sequence, the transport header must contain sequence information to enable the transport layer on the receiving end to get the pieces back together in the right order before handing the received message up to the layer above.

    End-to-end layers
    Unlike the lower “subnet” layers whose protocol is between immediately adjacent nodes, the transport layer and the layers above are true “source to destination” or end-to-end layers, and are not concerned with the details of the underlying communications facility. Transport layer software (and software above it) on the source station carries on a conversation with similar software on the destination station by using message headers and control messages.

    SESSION LAYER
    The session layer allows session establishment between processes running on different stations. It provides:
    Session establishment, maintenance and termination: allows two application processes on different machines to establish, use and terminate a connection, called a session.
    Session support: performs the functions that allow these processes to communicate over the network, performing security, name recognition, logging, and so on.

    PRESENTATION LAYER
    The presentation layer formats the data to be presented to the application layer. It can be viewed as the translator for the network. This layer may translate data from a format used by the application layer into a common format at the sending station, then translate the common format to a format known to the application layer at the receiving station.

    The presentation layer provides:
    Character code translation: for example, ASCII to EBCDIC.
    Data conversion: bit order, CR-CR/LF, integer-floating point, and so on.
    Data compression: reduces the number of bits that need to be transmitted on the network.
    Data encryption: encrypt data for security purposes. For example, password encryption.

    APPLICATION LAYER
    The application layer serves as the window for users and application processes to access network services. This layer contains a variety of commonly needed functions:
    Resource sharing and device redirection
    Remote file access
    Remote printer access
    Inter-process communication
    Network management
    Directory services
    Electronic messaging (such as mail)
    Network virtual terminals

    The following were incorrect answers:
    Application Layer – The application layer serves as the window for users and application processes to access network services.

    Presentation layer – The presentation layer formats the data to be presented to the application layer. It can be viewed as the translator for the network. This layer may translate data from a format used by the application layer into a common format at the sending station, then translate the common format to a format known to the application layer at the receiving station.

    Transport layer – The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.

    Reference:

    CISA review manual 2014 Page number 260

  4. Which of the following layer of an OSI model ensures that messages are delivered error-free, in sequence, and with no losses or duplications?

    • Application layer
    • Presentation layer
    • Session layer
    • Transport layer
    Explanation:

    The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.

    The size and complexity of a transport protocol depends on the type of service it can get from the network layer. For a reliable network layer with virtual circuit capability, a minimal transport layer is required. If the network layer is unreliable and/or only supports datagram’s, the transport protocol should include extensive error detection and recovery.

    The transport layer provides:
    Message segmentation: accepts a message from the (session) layer above it, splits the message into smaller units (if not already small enough), and passes the smaller units down to the network layer. The transport layer at the destination station reassembles the message.
    Message acknowledgment: provides reliable end-to-end message delivery with acknowledgments.
    Message traffic control: tells the transmitting station to “back-off” when no message buffers are available.
    Session multiplexing: multiplexes several message streams, or sessions onto one logical link and keeps track of which messages belong to which sessions (see session layer).

    For your exam you should know below information about OSI model:

    The Open Systems Interconnection model (OSI) is a conceptual model that characterizes and standardizes the internal functions of a communication system by partitioning it into abstraction layers. The model is a product of the Open Systems Interconnection project at the International Organization for Standardization (ISO), maintained by the identification ISO/IEC 7498-1.

    The model groups communication functions into seven logical layers. A layer serves the layer above it and is served by the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of that path. Two instances at one layer are connected by a horizontal.
    OSI Model

    CISA Certified Information Systems Auditor Part 67 Q04 074
    CISA Certified Information Systems Auditor Part 67 Q04 074

    PHYSICAL LAYER
    The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. It describes the electrical/optical, mechanical, and functional interfaces to the physical medium, and carries the signals for all of the higher layers. It provides:

    Data encoding: modifies the simple digital signal pattern (1s and 0s) used by the PC to better accommodate the characteristics of the physical medium, and to aid in bit and frame synchronization. It determines:
    What signal state represents a binary 1
    How the receiving station knows when a “bit-time” starts
    How the receiving station delimits a frame

    DATA LINK LAYER
    The data link layer provides error-free transfer of data frames from one node to another over the physical layer, allowing layers above it to assume virtually error-free transmission over the link. To do this, the data link layer provides:

    Link establishment and termination: establishes and terminates the logical link between two nodes.
    Frame traffic control: tells the transmitting node to “back-off” when no frame buffers are available.
    Frame sequencing: transmits/receives frames sequentially.
    Frame acknowledgment: provides/expects frame acknowledgments. Detects and recovers from errors that occur in the physical layer by retransmitting non-acknowledged frames and handling duplicate frame receipt.
    Frame delimiting: creates and recognizes frame boundaries.
    Frame error checking: checks received frames for integrity.
    Media access management: determines when the node “has the right” to use the physical medium.

    NETWORK LAYER
    The network layer controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service, and other factors. It provides:
    Routing: routes frames among networks.
    Subnet traffic control: routers (network layer intermediate systems) can instruct a sending station to “throttle back” its frame transmission when the router’s buffer fills up.
    Frame fragmentation: if it determines that a downstream router’s maximum transmission unit (MTU) size is less than the frame size, a router can fragment a frame for transmission and re-assembly at the destination station.
    Logical-physical address mapping: translates logical addresses, or names, into physical addresses.
    Subnet usage accounting: has accounting functions to keep track of frames forwarded by subnet intermediate systems, to produce billing information.

    Communications Subnet
    The network layer software must build headers so that the network layer software residing in the subnet intermediate systems can recognize them and use them to route data to the destination address.

    This layer relieves the upper layers of the need to know anything about the data transmission and intermediate switching technologies used to connect systems. It establishes, maintains and terminates connections across the intervening communications facility (one or several intermediate systems in the communication subnet).

    In the network layer and the layers below, peer protocols exist between a node and its immediate neighbor, but the neighbor may be a node through which data is routed, not the destination station. The source and destination stations may be separated by many intermediate systems.

    TRANSPORT LAYER
    The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.

    The size and complexity of a transport protocol depends on the type of service it can get from the network layer. For a reliable network layer with virtual circuit capability, a minimal transport layer is required. If the network layer is unreliable and/or only supports datagram’s, the transport protocol should include extensive error detection and recovery.

    The transport layer provides:
    Message segmentation: accepts a message from the (session) layer above it, splits the message into smaller units (if not already small enough), and passes the smaller units down to the network layer. The transport layer at the destination station reassembles the message.
    Message acknowledgment: provides reliable end-to-end message delivery with acknowledgments.
    Message traffic control: tells the transmitting station to “back-off” when no message buffers are available.
    Session multiplexing: multiplexes several message streams, or sessions onto one logical link and keeps track of which messages belong to which sessions (see session layer).

    Typically, the transport layer can accept relatively large messages, but there are strict message size limits imposed by the network (or lower) layer. Consequently, the transport layer must break up the messages into smaller units, or frames, pretending a header to each frame.

    The transport layer header information must then include control information, such as message start and message end flags, to enable the transport layer on the other end to recognize message boundaries. In addition, if the lower layers do not maintain sequence, the transport header must contain sequence information to enable the transport layer on the receiving end to get the pieces back together in the right order before handing the received message up to the layer above.

    End-to-end layers
    Unlike the lower “subnet” layers whose protocol is between immediately adjacent nodes, the transport layer and the layers above are true “source to destination” or end-to-end layers, and are not concerned with the details of the underlying communications facility. Transport layer software (and software above it) on the source station carries on a conversation with similar software on the destination station by using message headers and control messages.

    SESSION LAYER
    The session layer allows session establishment between processes running on different stations. It provides:
    Session establishment, maintenance and termination: allows two application processes on different machines to establish, use and terminate a connection, called a session.
    Session support: performs the functions that allow these processes to communicate over the network, performing security, name recognition, logging, and so on.

    PRESENTATION LAYER
    The presentation layer formats the data to be presented to the application layer. It can be viewed as the translator for the network. This layer may translate data from a format used by the application layer into a common format at the sending station, then translate the common format to a format known to the application layer at the receiving station.

    The presentation layer provides:
    Character code translation: for example, ASCII to EBCDIC.
    Data conversion: bit order, CR-CR/LF, integer-floating point, and so on.
    Data compression: reduces the number of bits that need to be transmitted on the network.
    Data encryption: encrypt data for security purposes. For example, password encryption.

    APPLICATION LAYER
    The application layer serves as the window for users and application processes to access network services. This layer contains a variety of commonly needed functions:
    Resource sharing and device redirection
    Remote file access
    Remote printer access
    Inter-process communication
    Network management
    Directory services
    Electronic messaging (such as mail)
    Network virtual terminals

    The following were incorrect answers:
    Application Layer – The application layer serves as the window for users and application processes to access network services.

    Presentation layer – The presentation layer formats the data to be presented to the application layer. It can be viewed as the translator for the network. This layer may translate data from a format used by the application layer into a common format at the sending station, then translate the common format to a format known to the application layer at the receiving station.

    Session layer – The session layer allows session establishment between processes running on different stations.

    Reference:

    CISA review manual 2014 Page number 260

  5. Which of the following layer of an OSI model responsible for routing and forwarding of a network packets?

    • Transport Layer
    • Network Layer
    • Data Link Layer
    • Physical Layer
    Explanation:

    The network layer controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service, and other factors.

    For CISA exam you should know below information about OSI model:

    The Open Systems Interconnection model (OSI) is a conceptual model that characterizes and standardizes the internal functions of a communication system by partitioning it into abstraction layers. The model is a product of the Open Systems Interconnection project at the International Organization for Standardization (ISO), maintained by the identification ISO/IEC 7498-1.

    The model groups communication functions into seven logical layers. A layer serves the layer above it and is served by the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of that path. Two instances at one layer are connected by a horizontal. OSI Model

    CISA Certified Information Systems Auditor Part 67 Q05 075
    CISA Certified Information Systems Auditor Part 67 Q05 075

    PHYSICAL LAYER
    The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. It describes the electrical/optical, mechanical, and functional interfaces to the physical medium, and carries the signals for all of the higher layers. It provides:

    Data encoding: modifies the simple digital signal pattern (1s and 0s) used by the PC to better accommodate the characteristics of the physical medium, and to aid in bit and frame synchronization. It determines:
    What signal state represents a binary 1
    How the receiving station knows when a “bit-time” starts
    How the receiving station delimits a frame

    DATA LINK LAYER
    The data link layer provides error-free transfer of data frames from one node to another over the physical layer, allowing layers above it to assume virtually error-free transmission over the link. To do this, the data link layer provides:

    Link establishment and termination: establishes and terminates the logical link between two nodes.
    Frame traffic control: tells the transmitting node to “back-off” when no frame buffers are available.
    Frame sequencing: transmits/receives frames sequentially.
    Frame acknowledgment: provides/expects frame acknowledgments. Detects and recovers from errors that occur in the physical layer by retransmitting non-acknowledged frames and handling duplicate frame receipt.
    Frame delimiting: creates and recognizes frame boundaries.
    Frame error checking: checks received frames for integrity.
    Media access management: determines when the node “has the right” to use the physical medium.

    NETWORK LAYER
    The network layer controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service, and other factors. It provides:
    Routing: routes frames among networks.
    Subnet traffic control: routers (network layer intermediate systems) can instruct a sending station to “throttle back” its frame transmission when the router’s buffer fills up.
    Frame fragmentation: if it determines that a downstream router’s maximum transmission unit (MTU) size is less than the frame size, a router can fragment a frame for transmission and re-assembly at the destination station.
    Logical-physical address mapping: translates logical addresses, or names, into physical addresses.
    Subnet usage accounting: has accounting functions to keep track of frames forwarded by subnet intermediate systems, to produce billing information.

    Communications Subnet
    The network layer software must build headers so that the network layer software residing in the subnet intermediate systems can recognize them and use them to route data to the destination address.

    This layer relieves the upper layers of the need to know anything about the data transmission and intermediate switching technologies used to connect systems. It establishes, maintains and terminates connections across the intervening communications facility (one or several intermediate systems in the communication subnet).

    In the network layer and the layers below, peer protocols exist between a node and its immediate neighbor, but the neighbor may be a node through which data is routed, not the destination station. The source and destination stations may be separated by many intermediate systems.

    TRANSPORT LAYER
    The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.

    The size and complexity of a transport protocol depends on the type of service it can get from the network layer. For a reliable network layer with virtual circuit capability, a minimal transport layer is required. If the network layer is unreliable and/or only supports datagram’s, the transport protocol should include extensive error detection and recovery.

    The transport layer provides:
    Message segmentation: accepts a message from the (session) layer above it, splits the message into smaller units (if not already small enough), and passes the smaller units down to the network layer. The transport layer at the destination station reassembles the message.
    Message acknowledgment: provides reliable end-to-end message delivery with acknowledgments.
    Message traffic control: tells the transmitting station to “back-off” when no message buffers are available.
    Session multiplexing: multiplexes several message streams, or sessions onto one logical link and keeps track of which messages belong to which sessions (see session layer).

    Typically, the transport layer can accept relatively large messages, but there are strict message size limits imposed by the network (or lower) layer. Consequently, the transport layer must break up the messages into smaller units, or frames, pretending a header to each frame.

    The transport layer header information must then include control information, such as message start and message end flags, to enable the transport layer on the other end to recognize message boundaries. In addition, if the lower layers do not maintain sequence, the transport header must contain sequence information to enable the transport layer on the receiving end to get the pieces back together in the right order before handing the received message up to the layer above.

    End-to-end layers
    Unlike the lower “subnet” layers whose protocol is between immediately adjacent nodes, the transport layer and the layers above are true “source to destination” or end-to-end layers, and are not concerned with the details of the underlying communications facility. Transport layer software (and software above it) on the source station carries on a conversation with similar software on the destination station by using message headers and control messages.

    SESSION LAYER
    The session layer allows session establishment between processes running on different stations. It provides:
    Session establishment, maintenance and termination: allows two application processes on different machines to establish, use and terminate a connection, called a session.
    Session support: performs the functions that allow these processes to communicate over the network, performing security, name recognition, logging, and so on.

    PRESENTATION LAYER
    The presentation layer formats the data to be presented to the application layer. It can be viewed as the translator for the network. This layer may translate data from a format used by the application layer into a common format at the sending station, then translate the common format to a format known to the application layer at the receiving station.

    The presentation layer provides:
    Character code translation: for example, ASCII to EBCDIC.
    Data conversion: bit order, CR-CR/LF, integer-floating point, and so on.
    Data compression: reduces the number of bits that need to be transmitted on the network.
    Data encryption: encrypt data for security purposes. For example, password encryption.

    APPLICATION LAYER
    The application layer serves as the window for users and application processes to access network services. This layer contains a variety of commonly needed functions:
    Resource sharing and device redirection
    Remote file access
    Remote printer access
    Inter-process communication
    Network management
    Directory services
    Electronic messaging (such as mail)
    Network virtual terminals

    The following were incorrect answers:
    Transport layer – The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.
    Data link layer – The data link layer provides error-free transfer of data frames from one node to another over the physical layer, allowing layers above it to assume virtually error-free transmission over the link.
    Physical Layer – The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. It describes the electrical/optical, mechanical, and functional interfaces to the physical medium, and carries the signals for all of the higher layers.

    Reference:

    CISA review manual 2014 Page number 260

  6. Which of the following layer of an OSI model encapsulates packets into frames?

    • Transport Layer
    • Network Layer
    • Data Link Layer
    • Physical Layer
    Explanation:

    The data link layer provides error-free transfer of data frames from one node to another over the physical layer, allowing layers above it to assume virtually error-free transmission over the link.

    For your exam you should know below information about OSI model:

    The Open Systems Interconnection model (OSI) is a conceptual model that characterizes and standardizes the internal functions of a communication system by partitioning it into abstraction layers. The model is a product of the Open Systems Interconnection project at the International Organization for Standardization (ISO), maintained by the identification ISO/IEC 7498-1.

    The model groups communication functions into seven logical layers. A layer serves the layer above it and is served by the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of that path. Two instances at one layer are connected by a horizontal.
    OSI Model

    CISA Certified Information Systems Auditor Part 67 Q06 076
    CISA Certified Information Systems Auditor Part 67 Q06 076

    PHYSICAL LAYER
    The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. It describes the electrical/optical, mechanical, and functional interfaces to the physical medium, and carries the signals for all of the higher layers. It provides:

    Data encoding: modifies the simple digital signal pattern (1s and 0s) used by the PC to better accommodate the characteristics of the physical medium, and to aid in bit and frame synchronization. It determines:
    What signal state represents a binary 1
    How the receiving station knows when a “bit-time” starts
    How the receiving station delimits a frame

    DATA LINK LAYER
    The data link layer provides error-free transfer of data frames from one node to another over the physical layer, allowing layers above it to assume virtually error-free transmission over the link. To do this, the data link layer provides:

    Link establishment and termination: establishes and terminates the logical link between two nodes.
    Frame traffic control: tells the transmitting node to “back-off” when no frame buffers are available.
    Frame sequencing: transmits/receives frames sequentially.
    Frame acknowledgment: provides/expects frame acknowledgments. Detects and recovers from errors that occur in the physical layer by retransmitting non-acknowledged frames and handling duplicate frame receipt.
    Frame delimiting: creates and recognizes frame boundaries.
    Frame error checking: checks received frames for integrity.
    Media access management: determines when the node “has the right” to use the physical medium.

    NETWORK LAYER
    The network layer controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service, and other factors. It provides:
    Routing: routes frames among networks.
    Subnet traffic control: routers (network layer intermediate systems) can instruct a sending station to “throttle back” its frame transmission when the router’s buffer fills up.
    Frame fragmentation: if it determines that a downstream router’s maximum transmission unit (MTU) size is less than the frame size, a router can fragment a frame for transmission and re-assembly at the destination station.
    Logical-physical address mapping: translates logical addresses, or names, into physical addresses.
    Subnet usage accounting: has accounting functions to keep track of frames forwarded by subnet intermediate systems, to produce billing information.

    Communications Subnet
    The network layer software must build headers so that the network layer software residing in the subnet intermediate systems can recognize them and use them to route data to the destination address.

    This layer relieves the upper layers of the need to know anything about the data transmission and intermediate switching technologies used to connect systems. It establishes, maintains and terminates connections across the intervening communications facility (one or several intermediate systems in the communication subnet).

    In the network layer and the layers below, peer protocols exist between a node and its immediate neighbor, but the neighbor may be a node through which data is routed, not the destination station. The source and destination stations may be separated by many intermediate systems.

    TRANSPORT LAYER
    The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.

    The size and complexity of a transport protocol depends on the type of service it can get from the network layer. For a reliable network layer with virtual circuit capability, a minimal transport layer is required. If the network layer is unreliable and/or only supports datagram’s, the transport protocol should include extensive error detection and recovery.

    The transport layer provides:
    Message segmentation: accepts a message from the (session) layer above it, splits the message into smaller units (if not already small enough), and passes the smaller units down to the network layer. The transport layer at the destination station reassembles the message.
    Message acknowledgment: provides reliable end-to-end message delivery with acknowledgments.
    Message traffic control: tells the transmitting station to “back-off” when no message buffers are available.
    Session multiplexing: multiplexes several message streams, or sessions onto one logical link and keeps track of which messages belong to which sessions (see session layer).

    Typically, the transport layer can accept relatively large messages, but there are strict message size limits imposed by the network (or lower) layer. Consequently, the transport layer must break up the messages into smaller units, or frames, pretending a header to each frame.

    The transport layer header information must then include control information, such as message start and message end flags, to enable the transport layer on the other end to recognize message boundaries. In addition, if the lower layers do not maintain sequence, the transport header must contain sequence information to enable the transport layer on the receiving end to get the pieces back together in the right order before handing the received message up to the layer above.

    End-to-end layers
    Unlike the lower “subnet” layers whose protocol is between immediately adjacent nodes, the transport layer and the layers above are true “source to destination” or end-to-end layers, and are not concerned with the details of the underlying communications facility. Transport layer software (and software above it) on the source station carries on a conversation with similar software on the destination station by using message headers and control messages.

    SESSION LAYER

    The session layer allows session establishment between processes running on different stations. It provides:
    Session establishment, maintenance and termination: allows two application processes on different machines to establish, use and terminate a connection, called a session.
    Session support: performs the functions that allow these processes to communicate over the network, performing security, name recognition, logging, and so on.

    PRESENTATION LAYER
    The presentation layer formats the data to be presented to the application layer. It can be viewed as the translator for the network. This layer may translate data from a format used by the application layer into a common format at the sending station, then translate the common format to a format known to the application layer at the receiving station.

    The presentation layer provides:
    Character code translation: for example, ASCII to EBCDIC.
    Data conversion: bit order, CR-CR/LF, integer-floating point, and so on.
    Data compression: reduces the number of bits that need to be transmitted on the network.
    Data encryption: encrypt data for security purposes. For example, password encryption.

    APPLICATION LAYER
    The application layer serves as the window for users and application processes to access network services. This layer contains a variety of commonly needed functions:
    Resource sharing and device redirection
    Remote file access
    Remote printer access
    Inter-process communication
    Network management
    Directory services
    Electronic messaging (such as mail)
    Network virtual terminals

    The following were incorrect answers:
    Transport layer – The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.
    Network layer – The network layer controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service, and other factors.
    Physical Layer – The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. It describes the electrical/optical, mechanical, and functional interfaces to the physical medium, and carries the signals for all of the higher layers.

    Reference:

    CISA review manual 2014 Page number 260

  7. Which of the following layer of an OSI model transmits and receives the bit stream as electrical, optical or radio signals over an appropriate medium or carrier?

    • Transport Layer
    • Network Layer
    • Data Link Layer
    • Physical Layer
    Explanation:

    The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. It describes the electrical/optical, mechanical, and functional interfaces to the physical medium, and carries the signals for all of the higher layers.

    For your exam you should know below information about OSI model:

    The Open Systems Interconnection model (OSI) is a conceptual model that characterizes and standardizes the internal functions of a communication system by partitioning it into abstraction layers. The model is a product of the Open Systems Interconnection project at the International Organization for Standardization (ISO), maintained by the identification ISO/IEC 7498-1.

    The model groups communication functions into seven logical layers. A layer serves the layer above it and is served by the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of that path. Two instances at one layer are connected by a horizontal.
    OSI Model

    CISA Certified Information Systems Auditor Part 67 Q07 077
    CISA Certified Information Systems Auditor Part 67 Q07 077

    PHYSICAL LAYER
    The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. It describes the electrical/optical, mechanical, and functional interfaces to the physical medium, and carries the signals for all of the higher layers. It provides:

    Data encoding: modifies the simple digital signal pattern (1s and 0s) used by the PC to better accommodate the characteristics of the physical medium, and to aid in bit and frame synchronization. It determines:
    What signal state represents a binary 1
    How the receiving station knows when a “bit-time” starts
    How the receiving station delimits a frame

    DATA LINK LAYER
    The data link layer provides error-free transfer of data frames from one node to another over the physical layer, allowing layers above it to assume virtually error-free transmission over the link. To do this, the data link layer provides:

    Link establishment and termination: establishes and terminates the logical link between two nodes.
    Frame traffic control: tells the transmitting node to “back-off” when no frame buffers are available.
    Frame sequencing: transmits/receives frames sequentially.
    Frame acknowledgment: provides/expects frame acknowledgments. Detects and recovers from errors that occur in the physical layer by retransmitting non-acknowledged frames and handling duplicate frame receipt.
    Frame delimiting: creates and recognizes frame boundaries.
    Frame error checking: checks received frames for integrity.
    Media access management: determines when the node “has the right” to use the physical medium.

    NETWORK LAYER
    The network layer controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service, and other factors. It provides:
    Routing: routes frames among networks.
    Subnet traffic control: routers (network layer intermediate systems) can instruct a sending station to “throttle back” its frame transmission when the router’s buffer fills up.
    Frame fragmentation: if it determines that a downstream router’s maximum transmission unit (MTU) size is less than the frame size, a router can fragment a frame for transmission and re-assembly at the destination station.
    Logical-physical address mapping: translates logical addresses, or names, into physical addresses.
    Subnet usage accounting: has accounting functions to keep track of frames forwarded by subnet intermediate systems, to produce billing information.

    Communications Subnet
    The network layer software must build headers so that the network layer software residing in the subnet intermediate systems can recognize them and use them to route data to the destination address.

    This layer relieves the upper layers of the need to know anything about the data transmission and intermediate switching technologies used to connect systems. It establishes, maintains and terminates connections across the intervening communications facility (one or several intermediate systems in the communication subnet).

    In the network layer and the layers below, peer protocols exist between a node and its immediate neighbor, but the neighbor may be a node through which data is routed, not the destination station. The source and destination stations may be separated by many intermediate systems.

    TRANSPORT LAYER
    The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.

    The size and complexity of a transport protocol depends on the type of service it can get from the network layer. For a reliable network layer with virtual circuit capability, a minimal transport layer is required. If the network layer is unreliable and/or only supports datagram’s, the transport protocol should include extensive error detection and recovery.

    The transport layer provides:
    Message segmentation: accepts a message from the (session) layer above it, splits the message into smaller units (if not already small enough), and passes the smaller units down to the network layer. The transport layer at the destination station reassembles the message.
    Message acknowledgment: provides reliable end-to-end message delivery with acknowledgments.
    Message traffic control: tells the transmitting station to “back-off” when no message buffers are available.
    Session multiplexing: multiplexes several message streams, or sessions onto one logical link and keeps track of which messages belong to which sessions (see session layer).

    Typically, the transport layer can accept relatively large messages, but there are strict message size limits imposed by the network (or lower) layer. Consequently, the transport layer must break up the messages into smaller units, or frames, pretending a header to each frame.

    The transport layer header information must then include control information, such as message start and message end flags, to enable the transport layer on the other end to recognize message boundaries. In addition, if the lower layers do not maintain sequence, the transport header must contain sequence information to enable the transport layer on the receiving end to get the pieces back together in the right order before handing the received message up to the layer above.

    End-to-end layers
    Unlike the lower “subnet” layers whose protocol is between immediately adjacent nodes, the transport layer and the layers above are true “source to destination” or end-to-end layers, and are not concerned with the details of the underlying communications facility. Transport layer software (and software above it) on the source station carries on a conversation with similar software on the destination station by using message headers and control messages.

    SESSION LAYER

    The session layer allows session establishment between processes running on different stations. It provides:
    Session establishment, maintenance and termination: allows two application processes on different machines to establish, use and terminate a connection, called a session.
    Session support: performs the functions that allow these processes to communicate over the network, performing security, name recognition, logging, and so on.

    PRESENTATION LAYER
    The presentation layer formats the data to be presented to the application layer. It can be viewed as the translator for the network. This layer may translate data from a format used by the application layer into a common format at the sending station, then translate the common format to a format known to the application layer at the receiving station.

    The presentation layer provides:
    Character code translation: for example, ASCII to EBCDIC.
    Data conversion: bit order, CR-CR/LF, integer-floating point, and so on.
    Data compression: reduces the number of bits that need to be transmitted on the network.
    Data encryption: encrypt data for security purposes. For example, password encryption.

    APPLICATION LAYER

    The application layer serves as the window for users and application processes to access network services. This layer contains a variety of commonly needed functions:
    Resource sharing and device redirection
    Remote file access
    Remote printer access
    Inter-process communication
    Network management
    Directory services
    Electronic messaging (such as mail)
    Network virtual terminals

    The following were incorrect answers:
    Transport layer – The transport layer ensures that messages are delivered error-free, in sequence, and with no losses or duplications. It relieves the higher layer protocols from any concern with the transfer of data between them and their peers.
    Network layer – The network layer controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service, and other factors.
    Data link layer – The data link layer provides error-free transfer of data frames from one node to another over the physical layer, allowing layers above it to assume virtually error-free transmission over the link.

    Reference:

    CISA review manual 2014 Page number 260

  8. Which of the following statement INCORRECTLY describes network device such as a Router?

    • Router creates a new header for each packet
    • Router builds a routing table based on MAC address
    • Router does not forward broadcast packet
    • Router assigns a different network address per port
    Explanation:

    The INCORRECTLY keyword is used in the question. You need to find out a statement which is not valid about router. Router builds a routing table based on IP address and not on MAC address.

    Difference between Router and Bridge:
    Router
    Bridge

    Creates a new header for each packet
    Does not alter header. Only reads the header
    Builds routing table based on IP address
    Build forwarding table based on MAC address
    Assigns a different network address per port

    Use the same network address for all ports

    Filters traffic based on IP address
    Filter traffic based on MAC address

    Does not forward broadcast packet

    Forward broadcast packet
    Does not forward traffic that contain destination address unknown to the router

    Forward traffic if destination address is unknown to bridge

    For your exam you should know below information about network devices:

    Repeaters
    A repeater provides the simplest type of connectivity, because it only repeats electrical signals between cable segments, which enables it to extend a network. Repeaters work at the physical layer and are add-on devices for extending a network connection over a greater distance. The device amplifies signals because signals attenuate the farther they have to travel.

    Repeaters can also work as line conditioners by actually cleaning up the signals. This works much better when amplifying digital signals than when amplifying analog signals, because digital signals are discrete units, which makes extraction of background noise from them much easier for the amplifier. If the device is amplifying analog signals, any accompanying noise often is amplified as well, which may further distort the signal.
    A hub is a multi-port repeater. A hub is often referred to as a concentrator because it is the physical communication device that allows several computers and devices to communicate with each other. A hub does not understand or work with IP or MAC addresses. When one system sends a signal to go to another system connected to it, the signal is broadcast to all the ports, and thus to all the systems connected to the concentrator.

    Repeater

    CISA Certified Information Systems Auditor Part 67 Q08 078
    CISA Certified Information Systems Auditor Part 67 Q08 078

    Bridges
    A bridge is a LAN device used to connect LAN segments. It works at the data link layer and therefore works with MAC addresses. A repeater does not work with addresses; it just forwards all signals it receives. When a frame arrives at a bridge, the bridge determines whether or not the MAC address is on the local network segment. If the MAC address is not on the local network segment, the bridge forwards the frame to the necessary network segment.

    Bridge

    CISA Certified Information Systems Auditor Part 67 Q08 079
    CISA Certified Information Systems Auditor Part 67 Q08 079

    Routers
    Routers are layer 3, or network layer, devices that are used to connect similar or different networks. (For example, they can connect two Ethernet LANs or an Ethernet LAN to a Token Ring LAN.) A router is a device that has two or more interfaces and a routing table so it knows how to get packets to their destinations. It can filter traffic based on access control lists (ACLs), and it fragments packets when necessary. Because routers have more network-level knowledge, they can perform higher-level functions, such as calculating the shortest and most economical path between the sending and receiving hosts.

    Router and Switch

    CISA Certified Information Systems Auditor Part 67 Q08 080
    CISA Certified Information Systems Auditor Part 67 Q08 080

    Switches
    Switches combine the functionality of a repeater and the functionality of a bridge. A switch amplifies the electrical signal, like a repeater, and has the built-in circuitry and intelligence of a bridge. It is a multi-port connection device that provides connections for individual computers or other hubs and switches.

    Gateways
    Gateway is a general term for software running on a device that connects two different environments and that many times acts as a translator for them or somehow restricts their interactions.

    Usually a gateway is needed when one environment speaks a different language, meaning it uses a certain protocol that the other environment does not understand. The gateway can translate Internetwork Packet Exchange (IPX) protocol packets to IP packets, accept mail from one type of mail server and format it so another type of mail server can accept and understand it, or connect and translate different data link technologies such as FDDI to Ethernet.

    Gateway Server

    CISA Certified Information Systems Auditor Part 67 Q08 081
    CISA Certified Information Systems Auditor Part 67 Q08 081

    The following were incorrect answers:
    The other options presented correctly describes about Router.

    Reference:
    CISA review manual 2014 Page number 263

  9. Identify the LAN topology from below diagram presented below:

    CISA Certified Information Systems Auditor Part 67 Q09 082
    CISA Certified Information Systems Auditor Part 67 Q09 082

    bus topology

    • Bus
    • Star
    • Ring
    • Mesh
    Explanation:

    For your exam you should know the information below related to LAN topologies:

    LAN Topologies
    Network topology is the physical arrangement of the various elements (links, nodes, etc.) of a computer network.

    Essentially, it is the topological structure of a network, and may be depicted physically or logically. Physical topology refers to the placement of the network’s various components, including device location and cable installation, while logical topology shows how data flows within a network, regardless of its physical design.

    Distances between nodes, physical interconnections, transmission rates, and/or signal types may differ between two networks, yet their topologies may be identical.

    Bus
    In local area networks where bus topology is used, each node is connected to a single cable. Each computer or server is connected to the single bus cable. A signal from the source travels in both directions to all machines connected on the bus cable until it finds the intended recipient. If the machine address does not match the intended address for the data, the machine ignores the data. Alternatively, if the data matches the machine address, the data is accepted. Since the bus topology consists of only one wire, it is rather inexpensive to implement when compared to other topologies. However, the low cost of implementing the technology is offset by the high cost of managing the network. Additionally, since only one cable is utilized, it can be the single point of failure. If the network cable is terminated on both ends and when without termination data transfer stop and when cable breaks, the entire network will be down.
    Bus topology

    CISA Certified Information Systems Auditor Part 67 Q09 083
    CISA Certified Information Systems Auditor Part 67 Q09 083

    Linear bus
    The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has exactly two endpoints (this is the ‘bus’, which is also commonly referred to as the backbone, or trunk) – all data that is transmitted between nodes in the network is transmitted over this common transmission medium and is able to be received by all nodes in the network simultaneously.

    Distributed bus
    The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has more than two endpoints that are created by adding branches to the main section of the transmission medium – the physical distributed bus topology functions in exactly the same fashion as the physical linear bus topology (i.e., all nodes share a common transmission medium).

    Star
    In local area networks with a star topology, each network host is connected to a central point with a point-to-point connection. In Star topology every node (computer workstation or any other peripheral) is connected to central node called hub or switch.

    The switch is the server and the peripherals are the clients. The network does not necessarily have to resemble a star to be classified as a star network, but all of the nodes on the network must be connected to one central device.

    All traffic that traverses the network passes through the central point. The central point acts as a signal repeater.

    The star topology is considered the easiest topology to design and implement. An advantage of the star topology is the simplicity of adding additional nodes. The primary disadvantage of the star topology is that the central point represents a single point of failure.
    Star Topology

    CISA Certified Information Systems Auditor Part 67 Q09 084
    CISA Certified Information Systems Auditor Part 67 Q09 084

    Ring
    A network topology that is set up in a circular fashion in which data travels around the ring in one direction and each device on the ring acts as a repeater to keep the signal strong as it travels. Each device incorporates a receiver for the incoming signal and a transmitter to send the data on to the next device in the ring.

    The network is dependent on the ability of the signal to travel around the ring. When a device sends data, it must travel through each device on the ring until it reaches its destination. Every node is a critical link. If one node goes down the whole link would be affected.

    Ring Topology

    CISA Certified Information Systems Auditor Part 67 Q09 085
    CISA Certified Information Systems Auditor Part 67 Q09 085

    Mesh
    The value of a fully meshed networks is proportional to the exponent of the number of subscribers, assuming that communicating groups of any two endpoints, up to and including all the endpoints, is approximated by Reed’s Law.

    A mesh network provides for high availability and redundancy. However, the cost of such network could be very expensive if dozens of devices are in the mesh.
    Mesh Topology

    CISA Certified Information Systems Auditor Part 67 Q09 086
    CISA Certified Information Systems Auditor Part 67 Q09 086

    Fully connected mesh topology
    A fully connected network is a communication network in which each of the nodes is connected to each other. In graph theory it known as a complete graph. A fully connected network doesn’t need to use switching nor broadcasting. However, its major disadvantage is that the number of connections grows quadratic ally with the number of nodes, so it is extremely impractical for large networks. A two-node network is technically a fully connected network.

    Partially connected mesh topology
    The type of network topology in which some of the nodes of the network are connected to more than one other node in the network with a point-to-point link – this makes it possible to take advantage of some of the redundancy that is provided by a physical fully connected mesh topology without the expense and complexity required for a connection between every node in the network.

    The following answers are incorrect:

    The other options presented are not valid.

    Reference:

    CISA review manual 2014, Page number 262

  10. Identify the network topology from below diagram presented below:

    CISA Certified Information Systems Auditor Part 67 Q10 087
    CISA Certified Information Systems Auditor Part 67 Q10 087

    Network Topology

    • Bus
    • Star
    • Ring
    • Mesh
    Explanation:

    For your exam you should know the information below related to LAN topologies:

    LAN Topologies
    Network topology is the physical arrangement of the various elements (links, nodes, etc.) of a computer network.

    Essentially, it is the topological structure of a network, and may be depicted physically or logically. Physical topology refers to the placement of the network’s various components, including device location and cable installation, while logical topology shows how data flows within a network, regardless of its physical design.

    Distances between nodes, physical interconnections, transmission rates, and/or signal types may differ between two networks, yet their topologies may be identical.

    Bus
    In local area networks where bus topology is used, each node is connected to a single cable. Each computer or server is connected to the single bus cable. A signal from the source travels in both directions to all machines connected on the bus cable until it finds the intended recipient. If the machine address does not match the intended address for the data, the machine ignores the data. Alternatively, if the data matches the machine address, the data is accepted. Since the bus topology consists of only one wire, it is rather inexpensive to implement when compared to other topologies. However, the low cost of implementing the technology is offset by the high cost of managing the network. Additionally, since only one cable is utilized, it can be the single point of failure. If the network cable is terminated on both ends and when without termination data transfer stop and when cable breaks, the entire network will be down.
    Bus topology

    Graphic from:

    CISA Certified Information Systems Auditor Part 67 Q10 088
    CISA Certified Information Systems Auditor Part 67 Q10 088

    Linear bus
    The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has exactly two endpoints (this is the ‘bus’, which is also commonly referred to as the backbone, or trunk) – all data that is transmitted between nodes in the network is transmitted over this common transmission medium and is able to be received by all nodes in the network simultaneously.

    Distributed bus
    The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has more than two endpoints that are created by adding branches to the main section of the transmission medium – the physical distributed bus topology functions in exactly the same fashion as the physical linear bus topology (i.e., all nodes share a common transmission medium).

    Star
    In local area networks with a star topology, each network host is connected to a central point with a point-to-point connection. In Star topology every node (computer workstation or any other peripheral) is connected to central node called hub or switch.

    The switch is the server and the peripherals are the clients. The network does not necessarily have to resemble a star to be classified as a star network, but all of the nodes on the network must be connected to one central device.

    All traffic that traverses the network passes through the central point. The central point acts as a signal repeater.

    The star topology is considered the easiest topology to design and implement. An advantage of the star topology is the simplicity of adding additional nodes. The primary disadvantage of the star topology is that the central point represents a single point of failure.
    Star Topology

    CISA Certified Information Systems Auditor Part 67 Q10 089
    CISA Certified Information Systems Auditor Part 67 Q10 089

    Ring
    A network topology that is set up in a circular fashion in which data travels around the ring in one direction and each device on the ring acts as a repeater to keep the signal strong as it travels. Each device incorporates a receiver for the incoming signal and a transmitter to send the data on to the next device in the ring.

    The network is dependent on the ability of the signal to travel around the ring. When a device sends data, it must travel through each device on the ring until it reaches its destination. Every node is a critical link. If one node goes down the whole link would be affected.

    Ring Topology

    CISA Certified Information Systems Auditor Part 67 Q10 090
    CISA Certified Information Systems Auditor Part 67 Q10 090

    Mesh

    The value of a fully meshed networks is proportional to the exponent of the number of subscribers, assuming that communicating groups of any two endpoints, up to and including all the endpoints, is approximated by Reed’s Law.

    A mesh network provides for high availability and redundancy. However, the cost of such network could be very expensive if dozens of devices are in the mesh.
    Mesh Topology

    CISA Certified Information Systems Auditor Part 67 Q10 091
    CISA Certified Information Systems Auditor Part 67 Q10 091

    Fully connected mesh topology
    A fully connected network is a communication network in which each of the nodes is connected to each other. In graph theory it known as a complete graph. A fully connected network doesn’t need to use switching nor broadcasting. However, its major disadvantage is that the number of connections grows quadratic ally with the number of nodes, so it is extremely impractical for large networks. A two-node network is technically a fully connected network.

    Partially connected mesh topology
    The type of network topology in which some of the nodes of the network are connected to more than one other node in the network with a point-to-point link – this makes it possible to take advantage of some of the redundancy that is provided by a physical fully connected mesh topology without the expense and complexity required for a connection between every node in the network.

    The following answers are incorrect:
    The other options presented are not valid.

    Reference:
    CISA review manual 2014, Page number 262

  11. Identify the network topology from below diagram presented below:

    CISA Certified Information Systems Auditor Part 67 Q11 092
    CISA Certified Information Systems Auditor Part 67 Q11 092

    Network Topology

    • Bus
    • Star
    • Ring
    • Mesh
    Explanation:

    For your exam you should know the information below related to LAN topologies:

    LAN Topologies
    Network topology is the physical arrangement of the various elements (links, nodes, etc.) of a computer network.

    Essentially, it is the topological structure of a network, and may be depicted physically or logically. Physical topology refers to the placement of the network’s various components, including device location and cable installation, while logical topology shows how data flows within a network, regardless of its physical design.

    Distances between nodes, physical interconnections, transmission rates, and/or signal types may differ between two networks, yet their topologies may be identical.

    Bus
    In local area networks where bus topology is used, each node is connected to a single cable. Each computer or server is connected to the single bus cable. A signal from the source travels in both directions to all machines connected on the bus cable until it finds the intended recipient. If the machine address does not match the intended address for the data, the machine ignores the data. Alternatively, if the data matches the machine address, the data is accepted. Since the bus topology consists of only one wire, it is rather inexpensive to implement when compared to other topologies. However, the low cost of implementing the technology is offset by the high cost of managing the network. Additionally, since only one cable is utilized, it can be the single point of failure. If the network cable is terminated on both ends and when without termination data transfer stop and when cable breaks, the entire network will be down.
    Bus topology

    CISA Certified Information Systems Auditor Part 67 Q11 093
    CISA Certified Information Systems Auditor Part 67 Q11 093

    Linear bus
    The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has exactly two endpoints (this is the ‘bus’, which is also commonly referred to as the backbone, or trunk) – all data that is transmitted between nodes in the network is transmitted over this common transmission medium and is able to be received by all nodes in the network simultaneously.

    Distributed bus
    The type of network topology in which all of the nodes of the network are connected to a common transmission medium which has more than two endpoints that are created by adding branches to the main section of the transmission medium – the physical distributed bus topology functions in exactly the same fashion as the physical linear bus topology (i.e., all nodes share a common transmission medium).

    Star

    In local area networks with a star topology, each network host is connected to a central point with a point-to-point connection. In Star topology every node (computer workstation or any other peripheral) is connected to central node called hub or switch.

    The switch is the server and the peripherals are the clients. The network does not necessarily have to resemble a star to be classified as a star network, but all of the nodes on the network must be connected to one central device.

    All traffic that traverses the network passes through the central point. The central point acts as a signal repeater.

    The star topology is considered the easiest topology to design and implement. An advantage of the star topology is the simplicity of adding additional nodes. The primary disadvantage of the star topology is that the central point represents a single point of failure.
    Star Topology

    CISA Certified Information Systems Auditor Part 67 Q11 094
    CISA Certified Information Systems Auditor Part 67 Q11 094

    Ring

    A network topology that is set up in a circular fashion in which data travels around the ring in one direction and each device on the ring acts as a repeater to keep the signal strong as it travels. Each device incorporates a receiver for the incoming signal and a transmitter to send the data on to the next device in the ring.

    The network is dependent on the ability of the signal to travel around the ring. When a device sends data, it must travel through each device on the ring until it reaches its destination. Every node is a critical link. If one node goes down the whole link would be affected.

    Ring Topology

    CISA Certified Information Systems Auditor Part 67 Q11 095
    CISA Certified Information Systems Auditor Part 67 Q11 095

    Mesh

    The value of a fully meshed networks is proportional to the exponent of the number of subscribers, assuming that communicating groups of any two endpoints, up to and including all the endpoints, is approximated by Reed’s Law.

    A mesh network provides for high availability and redundancy. However, the cost of such network could be very expensive if dozens of devices are in the mesh.
    Mesh Topology

    CISA Certified Information Systems Auditor Part 67 Q11 096
    CISA Certified Information Systems Auditor Part 67 Q11 096

    Fully connected mesh topology
    A fully connected network is a communication network in which each of the nodes is connected to each other. In graph theory it known as a complete graph. A fully connected network doesn’t need to use switching nor broadcasting. However, its major disadvantage is that the number of connections grows quadratic ally with the number of nodes, so it is extremely impractical for large networks. A two-node network is technically a fully connected network.

    Partially connected mesh topology
    The type of network topology in which some of the nodes of the network are connected to more than one other node in the network with a point-to-point link – this makes it possible to take advantage of some of the redundancy that is provided by a physical fully connected mesh topology without the expense and complexity required for a connection between every node in the network.

    The following answers are incorrect:
    The other options presented are not valid.

    Reference:
    CISA review manual 2014, Page number 262

  12. Identify the WAN message switching technique being used from the description presented below:

    “Data is routed in its entirety from the source node to the destination node, one hope at a time. During message routing, every intermediate switch in the network stores the whole message. If the entire network’s resources are engaged or the network becomes blocked, this WAN switching technology stores and delays the message until ample resources become available for effective transmission of the message. “

    • Message Switching
    • Packet switching
    • Circuit switching
    • Virtual Circuits
    Explanation:

    For your exam you should know below information about WAN message transmission technique:

    Message Switching
    Message switching is a network switching technique in which data is routed in its entirety from the source node to the destination node, one hope at a time. During message routing, every intermediate switch in the network stores the whole message. If the entire network’s resources are engaged or the network becomes blocked, the message-switched network stores and delays the message until ample resources become available for effective transmission of the message.

    Message Switching

    CISA Certified Information Systems Auditor Part 67 Q12 097
    CISA Certified Information Systems Auditor Part 67 Q12 097

    Packet Switching
    Refers to protocols in which messages are divided into packets before they are sent. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message.
    Packet Switching

    CISA Certified Information Systems Auditor Part 67 Q12 098
    CISA Certified Information Systems Auditor Part 67 Q12 098

    Circuit Switching
    Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel (circuit) through the network before the nodes may communicate.

    The circuit guarantees the full bandwidth of the channel and remains connected for the duration of the session. The circuit functions as if the nodes were physically connected similar to an electrical circuit.
    The defining example of a circuit-switched network is the early analog telephone network. When a call is made from one telephone to another, switches within the telephone exchanges create a continuous wire circuit between the two telephones, for as long as the call lasts.

    In circuit switching, the bit delay is constant during a connection, as opposed to packet switching, where packet queues may cause varying and potentially indefinitely long packet transfer delays. No circuit can be degraded by competing users because it is protected from use by other callers until the circuit is released and a new connection is set up. Even if no actual communication is taking place, the channel remains reserved and protected from competing users.

    Circuit Switching

    CISA Certified Information Systems Auditor Part 67 Q12 099
    CISA Certified Information Systems Auditor Part 67 Q12 099

    See a table below comparing Circuit Switched versus Packet Switched networks:
    Difference between Circuit and packet switching

    CISA Certified Information Systems Auditor Part 67 Q12 100
    CISA Certified Information Systems Auditor Part 67 Q12 100

    Virtual circuit
    In telecommunications and computer networks, a virtual circuit (VC), synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication.

    After a connection or virtual circuit is established between two nodes or application processes, a bit stream or byte stream may be delivered between the nodes; a virtual circuit protocol allows higher level protocols to avoid dealing with the division of data into segments, packets, or frames.

    Virtual circuit communication resembles circuit switching, since both are connection oriented, meaning that in both cases data is delivered in correct order, and signaling overhead is required during a connection establishment phase. However, circuit switching provides constant bit rate and latency, while these may vary in a virtual circuit service due to factors such as:

    varying packet queue lengths in the network nodes,
    varying bit rate generated by the application,
    varying load from other users sharing the same network resources by means of statistical multiplexing, etc.

    The following were incorrect answers:
    The other options presented are not valid choices.

    Reference:
    CISA review manual 2014 Page number 265

  13. In which of the following WAN message transmission technique messages are divided into packets before they are sent and each packet is then transmitted individually and can even follow different routes to its destination?

    • Message Switching
    • Packet switching
    • Circuit switching
    • Virtual Circuits
    Explanation:

    For your exam you should know below information about WAN message transmission technique:
    Message Switching

    Message switching is a network switching technique in which data is routed in its entirety from the source node to the destination node, one hope at a time. During message routing, every intermediate switch in the network stores the whole message. If the entire network’s resources are engaged or the network becomes blocked, the message-switched network stores and delays the message until ample resources become available for effective transmission of the message.

    Message Switching

    CISA Certified Information Systems Auditor Part 67 Q13 101
    CISA Certified Information Systems Auditor Part 67 Q13 101

    Packet Switching
    Refers to protocols in which messages are divided into packets before they are sent. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message.
    Packet Switching

    CISA Certified Information Systems Auditor Part 67 Q13 102
    CISA Certified Information Systems Auditor Part 67 Q13 102

    Circuit Switching
    Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel (circuit) through the network before the nodes may communicate.

    The circuit guarantees the full bandwidth of the channel and remains connected for the duration of the session. The circuit functions as if the nodes were physically connected similar to an electrical circuit.

    The defining example of a circuit-switched network is the early analog telephone network. When a call is made from one telephone to another, switches within the telephone exchanges create a continuous wire circuit between the two telephones, for as long as the call lasts.

    In circuit switching, the bit delay is constant during a connection, as opposed to packet switching, where packet queues may cause varying and potentially indefinitely long packet transfer delays. No circuit can be degraded by competing users because it is protected from use by other callers until the circuit is released and a new connection is set up. Even if no actual communication is taking place, the channel remains reserved and protected from competing users.

    Circuit Switching

    CISA Certified Information Systems Auditor Part 67 Q13 103
    CISA Certified Information Systems Auditor Part 67 Q13 103

    See a table below comparing Circuit Switched versus Packet Switched networks:
    Difference between Circuit and packet switching

    CISA Certified Information Systems Auditor Part 67 Q13 104
    CISA Certified Information Systems Auditor Part 67 Q13 104

    Virtual circuit
    In telecommunications and computer networks, a virtual circuit (VC), synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication.

    After a connection or virtual circuit is established between two nodes or application processes, a bit stream or byte stream may be delivered between the nodes; a virtual circuit protocol allows higher level protocols to avoid dealing with the division of data into segments, packets, or frames.

    Virtual circuit communication resembles circuit switching, since both are connection oriented, meaning that in both cases data is delivered in correct order, and signaling overhead is required during a connection establishment phase. However, circuit switching provides constant bit rate and latency, while these may vary in a virtual circuit service due to factors such as:

    varying packet queue lengths in the network nodes,
    varying bit rate generated by the application,
    varying load from other users sharing the same network resources by means of statistical multiplexing, etc.

    The following were incorrect answers:
    The other options presented are not valid choices.

    Reference:
    CISA review manual 2014 Page number 265

  14. In which of the following WAN message transmission technique does two network nodes establish a dedicated communications channel through the network before the nodes may communicate?

    • Message Switching
    • Packet switching
    • Circuit switching
    • Virtual Circuits
    Explanation:

    For your exam you should know below information about WAN message transmission technique:
    Message Switching
    Message switching is a network switching technique in which data is routed in its entirety from the source node to the destination node, one hope at a time. During message routing, every intermediate switch in the network stores the whole message. If the entire network’s resources are engaged or the network becomes blocked, the message-switched network stores and delays the message until ample resources become available for effective transmission of the message.

    Message Switching

    CISA Certified Information Systems Auditor Part 67 Q14 105
    CISA Certified Information Systems Auditor Part 67 Q14 105

    Packet Switching
    Refers to protocols in which messages are divided into packets before they are sent. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message.
    Packet Switching

    CISA Certified Information Systems Auditor Part 67 Q14 106
    CISA Certified Information Systems Auditor Part 67 Q14 106

    Circuit Switching
    Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel (circuit) through the network before the nodes may communicate.

    The circuit guarantees the full bandwidth of the channel and remains connected for the duration of the session. The circuit functions as if the nodes were physically connected similar to an electrical circuit.

    The defining example of a circuit-switched network is the early analog telephone network. When a call is made from one telephone to another, switches within the telephone exchanges create a continuous wire circuit between the two telephones, for as long as the call lasts.

    In circuit switching, the bit delay is constant during a connection, as opposed to packet switching, where packet queues may cause varying and potentially indefinitely long packet transfer delays. No circuit can be degraded by competing users because it is protected from use by other callers until the circuit is released and a new connection is set up. Even if no actual communication is taking place, the channel remains reserved and protected from competing users.

    Circuit Switching

    CISA Certified Information Systems Auditor Part 67 Q14 107
    CISA Certified Information Systems Auditor Part 67 Q14 107

    See a table below comparing Circuit Switched versus Packet Switched networks:
    Difference between Circuit and packet switching

    CISA Certified Information Systems Auditor Part 67 Q14 108
    CISA Certified Information Systems Auditor Part 67 Q14 108

    Virtual circuit
    In telecommunications and computer networks, a virtual circuit (VC), synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication.

    After a connection or virtual circuit is established between two nodes or application processes, a bit stream or byte stream may be delivered between the nodes; a virtual circuit protocol allows higher level protocols to avoid dealing with the division of data into segments, packets, or frames.

    Virtual circuit communication resembles circuit switching, since both are connection oriented, meaning that in both cases data is delivered in correct order, and signaling overhead is required during a connection establishment phase. However, circuit switching provides constant bit rate and latency, while these may vary in a virtual circuit service due to factors such as:

    varying packet queue lengths in the network nodes,
    varying bit rate generated by the application,
    varying load from other users sharing the same network resources by means of statistical multiplexing, etc.

    The following were incorrect answers:
    The other options presented are not valid choices.

    Reference:
    CISA review manual 2014 Page number 265

  15. Which of the following statement INCORRECTLY describes circuit switching technique?

    • Packet uses many different dynamic paths to get the same destination
    • Connection oriented virtual links
    • Fixed delays
    • Traffic travels in a predictable and constant manner
    Explanation:

    The word INCORRECTLY is the keyword used in the question. You need to find out a statement which is not valid about circuit switching.

    For your exam you should know below information about WAN message transmission technique:

    Message Switching

    Message switching is a network switching technique in which data is routed in its entirety from the source node to the destination node, one hope at a time. During message routing, every intermediate switch in the network stores the whole message. If the entire network’s resources are engaged or the network becomes blocked, the message-switched network stores and delays the message until ample resources become available for effective transmission of the message.

    Message Switching

    CISA Certified Information Systems Auditor Part 67 Q15 109
    CISA Certified Information Systems Auditor Part 67 Q15 109

    Packet Switching
    Refers to protocols in which messages are divided into packets before they are sent. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message.
    Packet Switching

    CISA Certified Information Systems Auditor Part 67 Q15 110
    CISA Certified Information Systems Auditor Part 67 Q15 110

    Circuit Switching
    Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel (circuit) through the network before the nodes may communicate.

    The circuit guarantees the full bandwidth of the channel and remains connected for the duration of the session. The circuit functions as if the nodes were physically connected similar to an electrical circuit.

    The defining example of a circuit-switched network is the early analog telephone network. When a call is made from one telephone to another, switches within the telephone exchanges create a continuous wire circuit between the two telephones, for as long as the call lasts.

    In circuit switching, the bit delay is constant during a connection, as opposed to packet switching, where packet queues may cause varying and potentially indefinitely long packet transfer delays. No circuit can be degraded by competing users because it is protected from use by other callers until the circuit is released and a new connection is set up. Even if no actual communication is taking place, the channel remains reserved and protected from competing users.

    Circuit Switching

    CISA Certified Information Systems Auditor Part 67 Q15 111
    CISA Certified Information Systems Auditor Part 67 Q15 111

    See a table below comparing Circuit Switched versus Packet Switched networks:
    Difference between Circuit and packet switching

    CISA Certified Information Systems Auditor Part 67 Q15 112
    CISA Certified Information Systems Auditor Part 67 Q15 112

    Virtual circuit
    In telecommunications and computer networks, a virtual circuit (VC), synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication.

    After a connection or virtual circuit is established between two nodes or application processes, a bit stream or byte stream may be delivered between the nodes; a virtual circuit protocol allows higher level protocols to avoid dealing with the division of data into segments, packets, or frames.

    Virtual circuit communication resembles circuit switching, since both are connection oriented, meaning that in both cases data is delivered in correct order, and signaling overhead is required during a connection establishment phase. However, circuit switching provides constant bit rate and latency, while these may vary in a virtual circuit service due to factors such as:

    varying packet queue lengths in the network nodes,
    varying bit rate generated by the application,
    varying load from other users sharing the same network resources by means of statistical multiplexing, etc.

    The following were incorrect answers:
    The other options presented correctly describes about circuit switching.

    Reference:
    CISA review manual 2014 Page number 265

  16. Which of the following statement INCORRECTLY describes packet switching technique?

    • Packet uses many different dynamic paths to get the same destination
    • Traffic is usually burst in nature
    • Fixed delays to reach each packet to destination
    • Usually carries data-oriented data
    Explanation:

    The word INCORRECTLY is the keyword used in the question. You need to find out a statement which is not valid about packet switching. As in the network switching, packet traverse different path, there will be always variable delay for each packet to reach to destination.

    For your exam you should know below information about WAN message transmission technique:

    Message Switching

    Message switching is a network switching technique in which data is routed in its entirety from the source node to the destination node, one hope at a time. During message routing, every intermediate switch in the network stores the whole message. If the entire network’s resources are engaged or the network becomes blocked, the message-switched network stores and delays the message until ample resources become available for effective transmission of the message.

    Message Switching

    CISA Certified Information Systems Auditor Part 67 Q16 113
    CISA Certified Information Systems Auditor Part 67 Q16 113

    Packet Switching
    Refers to protocols in which messages are divided into packets before they are sent. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message.
    Packet Switching

    CISA Certified Information Systems Auditor Part 67 Q16 114
    CISA Certified Information Systems Auditor Part 67 Q16 114

    Circuit Switching
    Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel (circuit) through the network before the nodes may communicate.

    The circuit guarantees the full bandwidth of the channel and remains connected for the duration of the session. The circuit functions as if the nodes were physically connected similar to an electrical circuit.
    The defining example of a circuit-switched network is the early analog telephone network. When a call is made from one telephone to another, switches within the telephone exchanges create a continuous wire circuit between the two telephones, for as long as the call lasts.

    In circuit switching, the bit delay is constant during a connection, as opposed to packet switching, where packet queues may cause varying and potentially indefinitely long packet transfer delays. No circuit can be degraded by competing users because it is protected from use by other callers until the circuit is released and a new connection is set up. Even if no actual communication is taking place, the channel remains reserved and protected from competing users.

    Circuit Switching

    CISA Certified Information Systems Auditor Part 67 Q16 115
    CISA Certified Information Systems Auditor Part 67 Q16 115

    See a table below comparing Circuit Switched versus Packet Switched networks:
    Difference between Circuit and packet switching

    CISA Certified Information Systems Auditor Part 67 Q16 116
    CISA Certified Information Systems Auditor Part 67 Q16 116

    Virtual circuit
    In telecommunications and computer networks, a virtual circuit (VC), synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication.

    After a connection or virtual circuit is established between two nodes or application processes, a bit stream or byte stream may be delivered between the nodes; a virtual circuit protocol allows higher level protocols to avoid dealing with the division of data into segments, packets, or frames.

    Virtual circuit communication resembles circuit switching, since both are connection oriented, meaning that in both cases data is delivered in correct order, and signaling overhead is required during a connection establishment phase. However, circuit switching provides constant bit rate and latency, while these may vary in a virtual circuit service due to factors such as:

    varying packet queue lengths in the network nodes,
    varying bit rate generated by the application,
    varying load from other users sharing the same network resources by means of statistical multiplexing, etc.

    The following were incorrect answers:
    The other options presented correctly describes about packet switching.

    Reference:
    CISA review manual 2014 Page number 265

  17. Which of the following protocol uses serial interface for communication between two computers in WAN technology?

    • Point-to-point protocol
    • X.25
    • Frame Relay
    • ISDN
    Explanation:

    PPP (Point-to-Point Protocol) is a protocol for communication between two computers using a serial interface, typically a personal computer using a MODEM connected by phone line to a server.

    For your exam you should know below information about WAN Technologies:

    Point-to-point protocol
    PPP (Point-to-Point Protocol) is a protocol for communication between two computers using a serial interface, typically a personal computer connected by phone line to a server. For example, your Internet server provider may provide you with a PPP connection so that the provider’s server can respond to your requests, pass them on to the Internet, and forward your requested Internet responses back to you. PPP uses the Internet protocol (IP) (and is designed to handle others). It is sometimes considered a member of the TCP/IP suite of protocols. Relative to the Open Systems Interconnection (OSI) reference model, PPP provides layer 2 (data-link layer) service. Essentially, it packages your computer’s TCP/IP packets and forwards them to the server where they can actually be put on the Internet.

    PPP is a full-duplex protocol that can be used on various physical media, including twisted pair or fiber optic lines or satellite transmission. It uses a variation of High Speed Data Link Control (HDLC) for packet encapsulation.

    PPP is usually preferred over the earlier de facto standard Serial Line Internet Protocol (SLIP) because it can handle synchronous as well as asynchronous communication. PPP can share a line with other users and it has error detection that SLIP lacks. Where a choice is possible, PPP is preferred.

    Point-to-point protocol

    CISA Certified Information Systems Auditor Part 67 Q17 117
    CISA Certified Information Systems Auditor Part 67 Q17 117

    X.25

    X.25 is an ITU-T standard protocol suite for packet switched wide area network (WAN) communication.
    X.25 is a packet switching technology which uses carrier switch to provide connectivity for many different networks.
    Subscribers are charged based on amount of bandwidth they use. Data are divided into 128 bytes and encapsulated in High Level Data Link Control (HDLC).
    X.25 works at network and data link layer of an OSI model.

    CISA Certified Information Systems Auditor Part 67 Q17 118
    CISA Certified Information Systems Auditor Part 67 Q17 118

    X.25

    Frame Relay

    Works on a packet switching
    Operates at data link layer of an OSI model
    Companies that pay more to ensure that a higher level of bandwidth will always be available, pay a committed information rate or CIR

    Two main types of equipment’s are used in Frame Relay
    1. Data Terminal Equipment (DTE) – Usually a customer owned device that provides a connectivity between company’s own network and the frame relay’s network.

    2. Data Circuit Terminal Equipment (DCE) – Service provider device that does the actual data transmission and switching in the frame relay cloud.

    The Frame relay cloud is the collection of DCE that provides that provides switching and data communication functionality. Frame relay is any to any service.

    CISA Certified Information Systems Auditor Part 67 Q17 119
    CISA Certified Information Systems Auditor Part 67 Q17 119

    Frame Relay

    Integrated Service Digital Network

    Enables data, voice and other types of traffic to travel over a medium in a digital manner previously used only for analog voice transmission.
    Same copper telephone wire is used.
    Provide digital point-to-point circuit switching medium.

    ISDN

    CISA Certified Information Systems Auditor Part 67 Q17 120
    CISA Certified Information Systems Auditor Part 67 Q17 120

    Asynchronous Transfer Mode (ATM)

    Uses Cell switching method
    High speed network technology used for LAN, MAN and WAN
    Like a frame relay it is connection oriented technology which creates and uses fixed channel
    Data are segmented into fixed size cell of 53 bytes
    Some companies have replaced FDDI back-end with ATM

    Asynchronous Transfer Mode

    Multiprotocol Label Switching (MPLS)
    Multiprotocol Label Switching (MPLS) is a standards-approved technology for speeding up network traffic flow and making it easier to manage. MPLS involves setting up a specific path for a given sequence of packets, identified by a label put in each packet, thus saving the time needed for a router to look up the address to the next node to forward the packet to. MPLS is called multiprotocol because it works with the Internet Protocol (IP), Asynchronous Transport Mode (ATM), and frame relay network protocols. With reference to the standard model for a network (the Open Systems Interconnection, or OSI model), MPLS allows most packets to be forwarded at the Layer 2 (switching) level rather than at the Layer 3 (routing) level. In addition to moving traffic faster overall, MPLS makes it easy to manage a network for quality of service (QoS). For these reasons, the technique is expected to be readily adopted as networks begin to carry more and different mixtures of traffic.

    MPLS

    CISA Certified Information Systems Auditor Part 67 Q17 121
    CISA Certified Information Systems Auditor Part 67 Q17 121

    The following answers are incorrect:

    X.25 – X.25 is an ITU-T standard protocol suite for packet switched wide area network (WAN) communication.X.25 is a packet switching technology which uses carrier switch to provide connectivity for many different networks.

    Frame Relay – The Frame relay cloud is the collection of DCE that provides that provides switching and data communication functionality. Frame relay is any to any service.

    ISDN -Enables data, voice and other types of traffic to travel over a medium in a digital manner previously used only for analog voice transmission. Same copper telephone wire is used. Provide digital point-to-point circuit switching medium.

    Reference:
    CISA review manual 2014 page number 266

  18. Which of the following is a ITU-T standard protocol suite for packet switched wide area network communication?

    • Point-to-point protocol
    • X.25
    • Frame Relay
    • ISDN
    Explanation:

    X.25 is an ITU-T standard protocol suite for packet switched wide area network (WAN) communication.X.25 is a packet switching technology which uses carrier switch to provide connectivity for many different networks.

    For your exam you should know below information about WAN Technologies:

    The following answers are incorrect:
    Point-to-point protocol – PPP (Point-to-Point Protocol) is a protocol for communication between two computers using a serial interface, typically a personal computer connected by phone line to a server.
    Frame Relay – The Frame relay cloud is the collection of DCE that provides that provides switching and data communication functionality. Frame relay is any to any service.

    ISDN -Enables data, voice and other types of traffic to travel over a medium in a digital manner previously used only for analog voice transmission. Same copper telephone wire is used. Provide digital point-to-point circuit switching medium.

    Reference:
    CISA review manual 2014 page number 266

  19. Which of the following device in Frame Relay WAN technique is generally customer owned device that provides a connectivity between company’s own network and the frame relays network?

    • DTE
    • DCE
    • DME
    • DLE
    Explanation:

    Data Terminal Equipment (DTE) – Usually a customer owned device that provides connectivity between company’s own network and the frame relay’s network.

    For your exam you should know below information about WAN Technologies:

    Point-to-point protocol
    PPP (Point-to-Point Protocol) is a protocol for communication between two computers using a serial interface, typically a personal computer connected by phone line to a server. For example, your Internet server provider may provide you with a PPP connection so that the provider’s server can respond to your requests, pass them on to the Internet, and forward your requested Internet responses back to you.

    PPP uses the Internet protocol (IP) (and is designed to handle other protocol as well). It is sometimes considered a member of the TCP/IP suite of protocols. Relative to the Open Systems Interconnection (OSI) reference model, PPP provides layer 2 (data-link layer) service. Essentially, it packages your computer’s TCP/IP packets and forwards them to the server where they can actually be put on the Internet.

    PPP is a full-duplex protocol that can be used on various physical media, including twisted pair or fiber optic lines or satellite transmission. It uses a variation of High Speed Data Link Control (HDLC) for packet encapsulation.

    PPP is usually preferred over the earlier de facto standard Serial Line Internet Protocol (SLIP) because it can handle synchronous as well as asynchronous communication. PPP can share a line with other users and it has error detection that SLIP lacks. Where a choice is possible, PPP is preferred.

    Point-to-point protocol

    CISA Certified Information Systems Auditor Part 67 Q19 122
    CISA Certified Information Systems Auditor Part 67 Q19 122

    X.25

    X.25 is an ITU-T standard protocol suite for packet switched wide area network (WAN) communication.
    X.25 is a packet switching technology which uses carrier switch to provide connectivity for many different networks.
    Subscribers are charged based on amount of bandwidth they use. Data are divided into 128 bytes and encapsulated in High Level Data Link Control (HDLC).
    X.25 works at network and data link layer of an OSI model.

    X.25

    CISA Certified Information Systems Auditor Part 67 Q19 123
    CISA Certified Information Systems Auditor Part 67 Q19 123

    Frame Relay

    Works as packet switching
    Operates at data link layer of an OSI model
    Companies that pay more to ensure that a higher level of bandwidth will always be available, pay a committed information rate or CIR

    Two main types of equipment’s are used in Frame Relay

    1. Data Terminal Equipment (DTE) – Usually a customer owned device that provides connectivity between company’s own network and the frame relay’s network.

    2. Data Circuit Terminal Equipment (DCE) – Service provider device that does the actual data transmission and switching in the frame relay cloud.

    The Frame relay cloud is the collection of DCE that provides that provides switching and data communication functionality. Frame relay is any to any service.

    Frame Relay

    CISA Certified Information Systems Auditor Part 67 Q19 124
    CISA Certified Information Systems Auditor Part 67 Q19 124

    Integrated Service Digital Network (ISDN)

    Enables data, voice and other types of traffic to travel over a medium in a digital manner previously used only for analog voice transmission.
    Runs on top of the Plain Old Telephone System (POTS). The same copper telephone wire is used.
    Provide digital point-to-point circuit switching medium.

    ISDN

    CISA Certified Information Systems Auditor Part 67 Q19 125
    CISA Certified Information Systems Auditor Part 67 Q19 125

    Asynchronous Transfer Mode (ATM)

    Uses Cell switching method
    High speed network technology used for LAN, MAN and WAN
    Like frame relay it is connection oriented technology which creates and uses fixed channel
    Data are segmented into fixed size cell of 53 bytes
    Some companies have replaces FDDI back-end with ATM

    Asynchronous Transfer Mode

    CISA Certified Information Systems Auditor Part 67 Q19 126
    CISA Certified Information Systems Auditor Part 67 Q19 126

    Multiprotocol Label Switching (MPLS)
    Multiprotocol Label Switching (MPLS) is a standard-approved technology for speeding up network traffic flow and making things easier to manage. MPLS involves setting up a specific path for a given sequence of packets, identified by a label put in each packet, thus saving the time needed for a router to look up the address to the next node to forward the packet to.

    MPLS is called multiprotocol because it works with the Internet Protocol (IP), Asynchronous Transport Mode (ATM), and frame relay network protocols.

    In reference to the Open Systems Interconnection, or OSI model, MPLS allows most packets to be forwarded at Layer 2 (switching) level rather than at the Layer 3 (routing) level.

    In addition to moving traffic faster overall, MPLS makes it easy to manage a network for quality of service (QoS). For these reasons, the technique is expected to be readily adopted as networks begin to carry more and different mixtures of traffic.
    MPLS

    CISA Certified Information Systems Auditor Part 67 Q19 127
    CISA Certified Information Systems Auditor Part 67 Q19 127

    The following answers are incorrect:

    DCE – Data Circuit Terminal Equipment (DCE) is a service provider device that does the actual data transmission and switching in the frame relay cloud.
    DME – Not a valid frame relay technique
    DLE – Not a valid frame relay technique

    Reference:
    CISA review manual 2014 page number 266

  20. Which of the following device in Frame Relay WAN technique is a service provider device that does the actual data transmission and switching in the frame relay cloud?

    • DTE
    • DCE
    • DME
    • DLE
    Explanation:

    Data Circuit Terminal Equipment (DCE) is a service provider device that does the actual data transmission and switching in the frame relay cloud.

    For your exam you should know below information about WAN Technologies:

    Point-to-point protocol
    PPP (Point-to-Point Protocol) is a protocol for communication between two computers using a serial interface, typically a personal computer connected by phone line to a server. For example, your Internet server provider may provide you with a PPP connection so that the provider’s server can respond to your requests, pass them on to the Internet, and forward your requested Internet responses back to you. PPP uses the Internet protocol (IP) (and is designed to handle others). It is sometimes considered a member of the TCP/IP suite of protocols. Relative to the Open Systems Interconnection (OSI) reference model, PPP provides layer 2 (data-link layer) service. Essentially, it packages your computer’s TCP/IP packets and forwards them to the server where they can actually be put on the Internet.

    PPP is a full-duplex protocol that can be used on various physical media, including twisted pair or fiber optic lines or satellite transmission. It uses a variation of High Speed Data Link Control (HDLC) for packet encapsulation.

    PPP is usually preferred over the earlier de facto standard Serial Line Internet Protocol (SLIP) because it can handle synchronous as well as asynchronous communication. PPP can share a line with other users and it has error detection that SLIP lacks. Where a choice is possible, PPP is preferred.

    CISA Certified Information Systems Auditor Part 67 Q20 128
    CISA Certified Information Systems Auditor Part 67 Q20 128

    Point-to-point protocol

    X.25

    X.25 is an ITU-T standard protocol suite for packet switched wide area network (WAN) communication.
    X.25 is a packet switching technology which uses carrier switch to provide connectivity for many different networks.
    Subscribers are charged based on amount of bandwidth they use. Data are divided into 128 bytes and encapsulated in High Level Data Link Control (HDLC).
    X.25 works at network and data link layer of an OSI model.

    X.25

    CISA Certified Information Systems Auditor Part 67 Q20 129
    CISA Certified Information Systems Auditor Part 67 Q20 129

    Frame Relay

    Works on a packet switching
    Operates at data link layer of an OSI model
    Companies that pay more to ensure that a higher level of bandwidth will always be available, pay a committed information rate or CIR

    Two main types of equipment’s  are used in Frame Relay
    1. Data Terminal Equipment (DTE) – Usually a customer owned device that provides a connectivity between company’s own network and the frame relay’s network.

    2. Data Circuit Terminal Equipment (DCE) – Service provider device that does the actual data transmission and switching in the frame relay cloud.

    The Frame relay cloud is the collection of DCE that provides that provides switching and data communication functionality. Frame relay is any to any service.

    Frame Relay

    Integrated Service Digital Network
    Enables data, voice and other types of traffic to travel over a medium in a digital manner previously used only for analog voice transmission.
    Same copper telephone wire is used.
    Provide digital point-to-point circuit switching medium

    ISDN

    CISA Certified Information Systems Auditor Part 67 Q20 130
    CISA Certified Information Systems Auditor Part 67 Q20 130

    Asynchronous Transfer Mode (ATM)

    Uses Cell switching method
    High speed network technology used for LAN, MAN and WAN
    Like a frame relay it is connection oriented technology which creates and uses fixed channel
    Data are segmented into fixed size cell of 53 bytes
    Some companies have replaces FDDI back-end with ATM

    Asynchronous Transfer Mode

    CISA Certified Information Systems Auditor Part 67 Q20 131
    CISA Certified Information Systems Auditor Part 67 Q20 131

    Multiprotocol Label Switching (MPLS)
    Multiprotocol Label Switching (MPLS) is a standards-approved technology for speeding up network traffic flow and making it easier to manage. MPLS involves setting up a specific path for a given sequence of packets, identified by a label put in each packet, thus saving the time needed for a router to look up the address to the next node to forward the packet to. MPLS is called multiprotocol because it works with the Internet Protocol (IP), Asynchronous Transport Mode (ATM), and frame relay network protocols. With reference to the standard model for a network (the Open Systems Interconnection, or OSI model), MPLS allows most packets to be forwarded at the Layer 2 (switching) level rather than at the Layer 3 (routing) level. In addition to moving traffic faster overall, MPLS makes it easy to manage a network for quality of service (QoS). For these reasons, the technique is expected to be readily adopted as networks begin to carry more and different mixtures of traffic.

    MPLS

    CISA Certified Information Systems Auditor Part 67 Q20 132
    CISA Certified Information Systems Auditor Part 67 Q20 132

    The following answers are incorrect:

    DTE – Data Terminal Equipment (DTE) is usually a customer owned device that provides a connectivity between company’s own network and the frame relay’s network.

    DME – Not a valid frame relay technique
    DLE – Not a valid frame relay technique

    Reference:
    CISA review manual 2014 page number 266