Question

In a class B subnet, we know the IP address of one host and the mask as given below:

IP address = 125.134.112.66

Mask = 255.255.224.0

What is the first address (Network address)?

1. 125.134.96.0
2. 125.134.112.0
3. 125.134.112.66
4. 125.134.0.0

Answer 1

Correct Answer - Option 1 : 125.134.96.0

The correct answer is "option 1".

CONCEPT:

Network address or First address is used for network identification.

The Network address is calculated by Bitwise AND operation of corresponding binary bits of IP Address & Subnet mask.

CALCULATION:

IP Address	125.134.112.66	01111101	10000110	01110000	01000010
Subnet Mask	255.255.224.0	11111111	11111111	11100000	00000000
Network  Address	125.134.96.0	01111101	10000110	01100000	00000000

Hence, IP Address 125.134.96.0 is the First address.