Subnetting Questions 5 | Find the Subnet Mask from IP Address

Subnetting Question 5

You have a network ID of 134.57.0.0 and you need to divide it into multiple subnets in which at least 600 host IDs for each subnet are available. You desire to have the largest amount of subnets available. Which subnet mask should you assign?

The Network ID is 134.57.0.0, this indicated it is a Class B Address

By default, in Class B Ip Address, 16 bits are reserved for the network and 16 bits are reserved for the host.

A/Q we have to find the maximum number of subnets with minimum 600 hosts on each.

Let’s find the host first,

The formula for finding the host is 2ⁿ – 2 (where n indicates the number of host bits and subtracted 2 because first and last IP address is always reserved for the network id and the broadcast id)

We required 10 host bits (11111111.11111111.11111100.00000000) (2¹⁰ – 2) = 1022

It means, on each network you will have 1022 host.

Now, let’s find the subnet mask

In first and second block, there are 8 network bits and its value is (2⁷ + 2⁶ + 2⁵ + 2⁴ + 2³ + 2² + 2¹ + 2⁰) . (2⁷ + 2⁶ + 2⁵ + 2⁴ + 2³ + 2² + 2¹ + 2⁰) = 255.255

In third block we have 6 network bits and its value is (2⁷ + 2⁶ + 2⁵ + 2⁴ + 2³ + 2²) = 252

In forth block there is no network bits. So, its value is 0

So, the subnet mask will be 255.255.252.0

Class B Subnetting Video Tutorial

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