# 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 1 Explanation:
 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 2 Explanation:

 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 0.5 D 0.75
GATE CSE 2022   Computer Network
Question 3 Explanation:
 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 4 Explanation:
 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
Question 5 Explanation:

There are 5 questions to complete.

### 3 thoughts on “Network Layer Protocol”

1. Q.No.92 Option-C to be read as “IP ensures that a packet is discarded if it is unable to reach its destination within a given number of hops”
pls rectify.