Data Communication and Computer Networks MCQ - Functions of OSI and TCP/IP Layers

11 Which one of the following statements is FALSE?

False. Packet switching results in less variation in delay than circuit switching.

12 The subnet mask for a particular network is 255.255.31.0 Which of the following pairs of IP addresses could belong to this network?

Subnet mask 255.255.31.0 shows class C network
So, class C network. IP address is
191.203.31.87 and 191.234.31.88

13 A subnet has been assigned a subnet mask of 255.255.255.192. What is the maximum number of hosts that can belong to this subnet?

Network Address = IP address BITWISE AND Subnet Mask
128.8.129.43 BITWISE-AND 255.255.31.0
= 128.8.1.0
128.8.161.55 BITWISE-AND 255.255.31.0
= 128.8.1.0.

14 The routing table of a router is shown below:

On which interfaces will the router forward packets addressed to destinations 128.75.43.16 and 192.12.17.10 respectively?

For 1st packet,
128.75.43.16 BITWISE-AND 255.255.255.0
= 128.75.43.0
128.75.43.16 BITWISE-AND 255.255.255.128
= 128.75.43.0
Now, since both these subnet masks are producing the same Network ID, hence The one with greater number of ones will be selected, and the packet will be forwarded there. Hence packet 1 will be forwarded to Eth1.
For 2nd packet,
192.12.17.10 BITWISE-AND 255.255.255.0
= 192.12.17.0
{Does not match with any of the network addresses}
192.12.17.10 BITWISE-AND 255.255.255.128
= 192.12.17.0
{Does not match with any of the network addresses}
192.12.17.10 BITWISE-AND 255.255.255.255
=192.12.17.10
{Does not match with any of the network addresses}
Hence, default interface must be selected for packet 2, i.e Interface Eth2.

15 An organization has a class B network and wishes to form subnets for 64 departments. The subnet mask would be

Since, we have to support 64 department so our first

= 252