ISRO2015-54

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)?

• A. 125.134.96.0
• B. 125.134.112.0
• C. 125.134.112.66
• D. 125.134.0.0

Answer 1

Answer A)

ANDing IP address and Network Mask we get Network Address

Mask                 11111111.11111111.11100000.00000000

IP Address         01111101.10000110.01110000.01000010

_______________________________________________________

     NID               01111101.10000110.01100000.00000000

Comments

how to convert ip address decimal value to binary easy way

---

no easy way other than division

---

ok i got the concept

Answer 2

Porocedure-1:

Network address=IP address  && Network Mask (and operation in binary equivalent).

Procedure-2:

Mask:255.255.224.0  So third octet having 3 bits netid and 5 bits host id

So block size is(2^5) i.e. 0,32,64,96,128......so on

By looking to the ip addres125.134.112.66, third octet 112 comes under 96 subnet. Hence Ans.