Subnetting and supernetting questions and answers

Given 172.18.0.0/16, divide the class B major network into

1) 2 equal subnets and list all the network addresses/new subnet mask

    Answer: 172.18.0.0/17 and 172.18.128.0/17

2) 4 equal subnets and list all the network addresses/new subnet mask

    Answer: 172.18.0.0/18, 172.18.64.0/18, 172.18.128.0/18, 172.18.192.0/18

3) 8 equal subnets and list all the network addresses/new subnet mask

   Answer: 172.18.0.0/19, 172.18.32.0/19, 172.18.64.0/19, 172.18.96.0/19, 172.18.128.0/19, 172.18.160.0/19, 172.18.192.0/19, 172.18.224.0/19

   Note: Every additional bit you use for subnetting will cause the number of subnets to double and the  number of hosts per subnet to halve.

Given the subnet address 172.18.64.0/19 and divide further into

4) 2 equal subnets and list all the network addresses/new subnet mask
   
    Answer: 172.18.64.0/20 and 172.18.80.0/20

    Note: You can divide a chosen subnet (not restricted to major classful networks only) to obtain more smaller subnets.

5) Determine 192.168.1.0/24's number of subnets and hosts supported

    Answer: 1 subnet and 254 hosts per subnet

6) Determine 192.168.1.0/25's number of subnets and hosts supported

    Answer: 2 subnets and 126 hosts per subnet

7) Determine 192.168.1.0/26's number of subnets and hosts supported

    Answer: 4 subnets and 62 hosts per subnet

    Note: The more subnets you have, the more network addresses and broadcast addresses you need to reserve from the original classful major network.

8) Summarize the following into 1 single summary route
192.168.0.0/30
192.168.0.4/30
192.168.0.8/30
192.168.0.16/29
192.168.4.0/30
192.168.5.0/30
192.168.6.0/30
192.168.7.0/29

Answer: 192.168.0.0/21

9) Summarize the following into 1 single summary route
192.168.68.0/24
192.168.96.0/24
192.168.80.0/24

Answer: 192.168.64.0/18

Note: Summary routes make the routing table smaller and the lookup faster.