UGC NET CSE | June 2014 | Part 3 | Question: 71

Question

A network on the Internet has a subnet mask of $255.255.240.0$. What is the maximum number of hosts it can handle ? 

• A. $1024$
• B. $2048$
• C. $4096$ 
• D. $8192$ 

Answer 1

Subnet Mask : - 255.255.240.0

$\underbrace{11111111 . 11111111 . 1111 }_{net\ id }\underbrace{0000.00000000 }_{host \ id}$

It is a class B network.For a class B network, the upper 16 bits form the network address and lower 16 bits are subnet and host fields.

of the lower 16 bits most significant 4 bits are 1111.This leaves 12 bits for the host number.So,4096(2¹²) host address exists.

First and Last address are special so the maximum number of address

=4096-2=4094

Comments

Why it is class B network?plz ans me

Answer 2

The given subnet mask's encoded IP address is 
11111111111111111111000000000000
12 bits are available for the hostid ==> 2^12 possible hostids.

so the maximum number of hosts on this subnet is 2^12 = 4096 hosts.

Comments

Host bits all zero's and all one's can't be used (one for netid and one for dba)  so 4096-2=4094

Answer 3

• maximum number of host=2^n-2 .
• we need to subtract 2 becz one is used for subnet id and other is used for DBA.
• 

Comments

Explanation easy to understand