Q. 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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Q. Which of the following statements is TRUE ?

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Q. Two popular routing algorithms are Distance Vector(DV) and Link State (LS) routing. Which of the following are true?
(S1) Count to infinity is a problem only with DV and not LS routing
(S2) In LS, the shortest path algorithm is run only at one node
(S3) In DV, the shortest path algorithm is run only at one node
(S4) DV requires lesser number of network messages than LS

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Q. Host X has IP address 192.168.1.97 and is connected through two routers R1 and R2 to an­other host Y with IP address 192.168.1.80. Router R1 has IP addresses 192.168.1.135 and 192.168.1.110. R2 has IP addresses 192.168.1.67 and 192.168.1.155. The netmask used in the network is 255.255.255.224.

Given the information above, how many distinct subnets are guaranteed to already exist in the network?

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Q. The transport layer protocols used for real time multimedia, file transfer, DNS and email, respectively are:

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Q. Which of the following transport layer protocols is used to support electronic mail?

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Q. Consider an instance of TCP’s Additive Increase Multiplicative Decrease (AIMD) algorithm where the window size at the start of the slow start phase is 2 MSS and the threshold at the start of the first transmission is 8 MSS. Assume that a timeout occurs during the fifth transmission. Find the congestion window size at the end of the tenth transmission.

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Q. A layer-4 firewall (a device that can look at all protocol headers up to the transport layer) CANNOT

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Q. While opening a TCP connection, the initial sequence number is to be derived using a time-of-day(ToD) clock that keeps running even when the host is down. The low order 32 bits of the counter of the ToD clock is to be used for the initial sequence numbers. The clock counter increments once per millisecond. The maximum packet lifetime is given to be 64s. Which one of the choices given below is closest to the minimum permissible rate at which sequence numbers used for packets of a connection can increase?

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Q. Which of the following system calls results in the sending of SYN packets?

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Q. In the slow start phase of the TCP congestion control algorithm, the size of the congestion window

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Q. Which one of the following uses UDP as the transport protocol?

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Q. Let the size of congestion window of a TCP connection be 32 KB when a timeout occurs. The round trip time of the connection is 100 msec and the maximum segment size used is 2 KB. The time taken (in msec) by the TCP connection to get back to 32 KB congestion window is _________.

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Q. Which one of the following socket API functions converts an unconnected active TCP socket into a passive socket.

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Q. Packets of the same session may be routed through different paths in

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Q. The maximum window size for data transmission using the selective reject protocol with n-bit frame sequence numbers is:

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Q. Which of the following functionalities must be implemented by a transport protocol over and above the network protocol ?

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Q. Which of the following is not true about User Datagram Protocol in transport layer?

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Q. 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?

1. If the sequence number of a segment is m, then the sequence
number of the subsequent segment is always m+1.
2. 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.
3. The size of the advertised window never changes during the
course of the TCP connection.
4. The number of unacknowledged bytes at the sender is always
less than or equal to the advertised window

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Q. A link has a transmission speed of 10^6 bits/sec. It uses data packets of size 1000 bytes each. Assume that the acknowledgment has negligible transmission delay, and that its propagation delay is the same as the data propagation delay. Also assume that the processing delays at nodes are negligible. The efficiency of the stop-and-wait protocol in this setup is exactly 25%. The value of the one-way propagation delay (in milliseconds) is ___________.

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