# Subnets in computer network

Question: Given: Class B IP address 169.202.0.0.

Network when divided into 4 sub networks, each one requires 16,000 IP addresses. They need to be assigned sequentially without gaps.

Find the sub networks.

Here is my solution:

Total IP addresses in 1 subnet are 16000 = 2^14 – 384 Bits required for subnet: 4 = 2^2 = 2 bits

Bits Required for Host id: 16000 = 214 =14 bits

Subnet 1: 169.202.0.0 To 169.202.62.127 = (62x256) +128=16000

Subnet 2: 169.202.62.128 To 169.202.125.255

Subnet 3: 169.202.126.0 To 169.202.188.127

However in the solution booklet something else was mentioned( solution given below) which confused me. Please help/guide me.

What do them mean by wasting few IP addresses and how are those particular ones selected. Moreover how did we get the solution given in the image below. Subnet 4: 169.202.10 111100.1000000 = 169.202.188.128 To 169.202.11 111011.1111111 = 169.202.251.255

• Can you clarify what about it confused you? What specifically is your question? What parts of it do you understand, and what is the first part you don't understand? Please edit your post to make your question more specific. – D.W. Dec 20 '17 at 17:13
• The title you have chosen is not well suited to representing your question. Please take some time to improve it; we have collected some advice here. Thank you! – Raphael Dec 21 '17 at 10:28

After subnetting the the network Id for any subnet will consists of two parts:

1. First part consisting of 1st 16 bits(from left side)
2. Subnet identifier which will be of 2 bits.

All addresses within a particular subnet must have the same network Id part.

Now consider subnet 2(created by u)and consider the 3rd octet from left.

• A subnet in this case needs only 16000 addresses. But If I use the last 14 bits for host id the subnet will get $2^{14}=16384$ addresses. Those 384 addresses will get wasted. – Kishan Kumar Dec 22 '17 at 7:28