Computer networks miscellaneous

Computer networks miscellaneous

Easy Questions

Computer Networks

Computer networks miscellaneous
  1. Suppose that the stop-and-wait protocol is used on a link with a bit rate of 64 kilobits per second and 20 milliseconds propagation delay. Assume that the transmission time for the acknowledgement and the processing time at nodes are negligible. Then the minimum frame size in bytes to achieve a link utilization of at least 50% is _________.








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    Given that B = 64 kbps
    Tp = 20 ms
    η ≥ 50%
    For η ≥ 50% ⇒ L ≥ BR
    ⇒ L = 64 × 103 × 2 × 20 × 10–3
    = 2560 bits = 320 bytes

    Correct Option: C

    Given that B = 64 kbps
    Tp = 20 ms
    η ≥ 50%
    For η ≥ 50% ⇒ L ≥ BR
    ⇒ L = 64 × 103 × 2 × 20 × 10–3
    = 2560 bits = 320 bytes

  1. In one of the pairs of protocols given below, both the protocols can use multiple TCP connections between the same client and the server. Which one is that?








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    HTTP (Hyper Text Transfer Protocol) and SMTP (Simple Message Transfer Protocol) protocols can use several TCP associations between the same client and the server.

    Correct Option: D

    HTTP (Hyper Text Transfer Protocol) and SMTP (Simple Message Transfer Protocol) protocols can use several TCP associations between the same client and the server.

  1. Suppose two hosts use a TCP connection to transfer a large file. Which of the following statements is/are FALSE with respect to the TCP connection?
    I. If the sequence number of a segment is m, then the sequence number of the subsequent segment is always m + 1.
    II. If the estimated round trip time at any given point of time is t sec the value of the retransmission timeout is always set to greater than or equal to t sec.
    III. The size of the advertised window never changes during the curse of the TCP connection.
    IV. The number of unacknowledged bytes at the sender is always less than or equal to the advertised window.








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    I : FALSE
    The sequence number of the subsequent segment depends on the number of 8-byte characters in the current segment.
    II : TRUE
    Depending on the value of a or expected RTT it may or may not be greater than 1.
    III : FALSE
    It is the size of the receiver's buffer that's never changed. Receive Window is the part of the receiver's buffer that's changing all the time depending on the processing ability at the receiver's side and the network traffic.
    IV : TRUE
    The number of unappreciated bytes that A sends cannot exceed the size of the receiver's window. But if it can't exceed the receiver's window, then it definitely has no way to exceed the receiver's buffer as the window size is always less than or equal to the buffer size. On the other hand, for urgent messages, the sender CAN send it in even although the receiver's buffer is full.

    Correct Option: B

    I : FALSE
    The sequence number of the subsequent segment depends on the number of 8-byte characters in the current segment.
    II : TRUE
    Depending on the value of a or expected RTT it may or may not be greater than 1.
    III : FALSE
    It is the size of the receiver's buffer that's never changed. Receive Window is the part of the receiver's buffer that's changing all the time depending on the processing ability at the receiver's side and the network traffic.
    IV : TRUE
    The number of unappreciated bytes that A sends cannot exceed the size of the receiver's window. But if it can't exceed the receiver's window, then it definitely has no way to exceed the receiver's buffer as the window size is always less than or equal to the buffer size. On the other hand, for urgent messages, the sender CAN send it in even although the receiver's buffer is full.

  1. Identify the correct sequence in which the following packets are transmitted on the network by a host when a browser requests a web page from a remote server, assuming that the host has just been restarted.








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    When a web browser requests any web page from a remote server then that request (URL address) is mapped to IP Address using DNS, then TCP synchronisation occurs. Finally HTTP verifies that the address exists in the web server or not.

    Correct Option: C

    When a web browser requests any web page from a remote server then that request (URL address) is mapped to IP Address using DNS, then TCP synchronisation occurs. Finally HTTP verifies that the address exists in the web server or not.

  1. An IP datagram of size 1000 bytes arrives at a router. The router has to forward this packet on a link whose MTU (maximum transmission unit) is 100 bytes. Assume that the size of the IP header is 20 bytes. The number of fragments that the IP datagram will be divided into for transmission is __________ .








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    Therefore the no. of fragments that are transferred in this case is 13.

    Correct Option: A


    Therefore the no. of fragments that are transferred in this case is 13.