CN |Gate-2012| Previous Year Questions| Set-9

Set-15 GATE-2006 CN

CN |Gate-2012| Computer Networks

  1. The protocol data unit (PDU) for the application layer in the Internet stack is [GATE – 2012]

a. segment
b. datagram
c. message
d. Frame

Answer : c)


  1. Which of the following transport layer protocols is used to support electronic mail? [GATE – 2012]

a. SMTP
b. IP
c. TCP
d. UDP

Answer : c)


  1. In the IPv4 addressing format, the number of networks allowed under Class C addresses is [GATE – 2012]

a. 214
b. 27
c. 224
d. 221

Answer  :d)


  1. An Internet Service Provider (ISP) has the following chunk of CIDR-based IP addresses available with it: 245.248.128.0/20. The ISP wants to give half of this chunk of addresses to Organization A, and a quarter to Organization B, while retaining the remaining with itself. Which of the following is a valid allocation of addresses to A and B? [GATE – 2012]

a. 245.248.136.0/21 and 245.248.128.0/22
b. 245.248.128.0/21 and 245.248.128.0/22
c. 245.248.132.0/22 and 245.248.132.0/21
d. 245.248.136.0/24 and 245.248.132.0/21

Answer : a)


  1. Consider a source computer (S) transmitting a file of size 106 bits to a destination computer (D) over a network of two routers (R1 and R2) and three links (L1, L2 and L3). L1 connects S to R1; L2 connects R1 to R2; and L3 connects R2 to D. Let each link be of length 100 km. Assume signals travel over each link at a speed of 108 meters per second. Assume that the link bandwidth on each link is 1Mbps. Let the file be broken down into 1000 packets each of size 1000 bits. Find the total sum of transmission and propagation delays in transmitting the file from S to D? [GATE – 2012]

a. 1005 ms
b. 1010 ms
c. 3000 ms
d. 3003 ms

Answer : a)


  1. 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. [GATE – 2012]

a. 8 MSS
b. 7 MSS
c. 14 MSS
d. 12 MSS

Answer : b)
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