Subnetting Questions 38 | Find the maximum number of subnets & host

Subnetting Questions 38

Enter the maximum number of valid subnets and usable hosts per subnet that you can get from the network 172.25.0.0/23

Solution

Hence, the IP Address starts from 172 it indicates it is a Class B Network an by default in class B network 16 bits are reserved for the network and 16 bits are reserved for the host.

A/Q the CIDR value is /23. It means we have to borrow another 7 bits from the third octet (16 + 7 = 13).

11111111 . 11111111 . 11111110 . 00000000

(2⁷ + 2⁶ + 2⁵ + 2⁴ + 2³ + 2² + 2¹ + 2⁰) . (2⁷ + 2⁶ + 2⁵ + 2⁴ + 2³ + 2² + 2¹ + 2⁰) . (2⁷ + 2⁶ + 2⁵ + 2⁴ + 2³ + 2² + 2¹) . 0

So, the subnet mask we get is 255.255.254.0

Let’s find the number of Subnet.

2ⁿ (n is the number of bits borrowed)

2⁷ = 128

So, the total number of subnet is 128

Let’s find the number of Host on each network,

2ⁿ – 2 (n is the number of host bits, substracted 2 because on every network first IP is the network ID and last IP is the broadcast ID)

2⁹ – 2

518

Therefor, there are 518 hosts available on each network.