Network Layer Protocol


Question 1
The forwarding table of a router is shown below.
\begin{array}{|c|c|c|c|} \hline \\ Subnet \; Number&Subnet \;Mask&Interface ID \\ \hline 200.150.0.0 &255.255.0.0& 1\\ \hline 200.150.64.0 &255.255.224.0 &2\\ \hline 200.150.68.0 &255.255.255.0 &3\\ \hline 200.150.68.64 &255.255.255.224 &4 \\ \hline Default & &0\\ \hline \end{array}
A packet addressed to a destination address 200.150.68.118 arrives at the router. It will be forwarded to the interface with ID _____.
A
1
B
2
C
3
D
4
GATE CSE 2023   Computer Network
Question 2
Which of the following statements is/are INCORRECT about the OSPF (Open Shortest Path First) routing protocol used in the Internet?
A
OSPF implements Bellman-Ford algorithm to find shortest paths.
B
OSPF uses Dijkstra's shortest path algorithm to implement least-cost path routing
C
OSPF is used as an inter-domain routing protocol
D
OSPF implements hierarchical routing.
GATE CSE 2023   Computer Network


Question 3
Consider a network with three routers P, Q, R shown in the figure below. All the links have cost of unity.

The routers exchange distance vector routing information and have converged on the routing tables, after which the link Q-R fails. Assume that P and Q send out routing updates at random times, each at the same average rate. The probability of a routing loop formation (rounded off to one decimal place) between P and Q, leading to count-to-infinity problem, is ____
A
0.25
B
0.33
C
0.50
D
0.75
GATE CSE 2022   Computer Network
Question 4
Consider routing table of an organization's router shown below:
\begin{array}{|l|l|l|} Subnet Number & Subnet Mask & Next Hop \\ 12.20.164.0 & 255.255.252.0 & R1 \\ 12.20.170.0 & 255.255.254.0 & R2 \\ 12.20.168.0 & 255.255.254.0 & Interface 0 \\ 12.20.166.0 & 255.255.254.0 & Interface 1 \\ default & ~ & R3 \\ \hline \end{array}
Which of the following prefixes in CIDR notation can be collectively used to correctly aggregate all of the subnets in the routing table?
MSQ
A
12.20.164.0/20
B
12.20.164.0/22
C
12.20.164.0/21
D
12.20.168.0/22
GATE CSE 2022   Computer Network
Question 5
Consider an enterprise network with two Ethernet segments, a web server and a firewall, connected via three routers as shown below.

What is the number of subnets inside the enterprise network?
A
3
B
12
C
6
D
8
GATE CSE 2022   Computer Network




There are 5 questions to complete.

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