Answer to Question #151224 in Computer Networks for Abdul Rehman Siddiqui

Question

Perform the subnetting on the below IP Address and find out the number of networks, network of, first host, last host, and broadcast id of each network.
IP Address:
120.0.0.0/20

Answer 1

Network 120.0.0.0/20 is a class B network

Since 20 bits are used for network the remaining 32-20= 12 will be used for host address.

To get the total number of hosts 2^12=4096 hosts but the first and last address are normally not used

So usable hosts will be 4096-2= 4094

To get number of networks we take total number of hosts(4096) divide by 256

4096/256= 16 networks

First usable IP address will be 120.0.0.1

Last usable IP address will be 120.0.15.254

Since broadcast address I normally the last address of the network hence: -

All 16 of the Possible /20 Networks for 120.0.x.x

Network Address        Usable Host Range                                Broadcast Address:

 

120.0.0.0            120.0.0.1 - 120.0.15.254                                     120.0.15.255

120.0.16.0           120.0.16.1 - 120.0.31.254                                  120.0.31.255

 

120.0.32.0           120.0.32.1 - 120.0.47.254                                   120.0.47.255

 

120.0.48.0           120.0.48.1 - 120.0.63.254                                    120.0.63.255

 

120.0.64.0           120.0.64.1 - 120.0.79.254                                     120.0.79.255

 

120.0.80.0           120.0.80.1 - 120.0.95.254                                      120.0.95.255

 

120.0.96.0           120.0.96.1 - 120.0.111.254                                    120.0.111.255

 

120.0.112.0        120.0.112.1 - 120.0.127.254                                   120.0.127.255

 

120.0.128.0        120.0.128.1 - 120.0.143.254                                    120.0.143.255

 

120.0.144.0        120.0.144.1 - 120.0.159.254                                    120.0.159.255

 

120.0.160.0        120.0.160.1 - 120.0.175.254                                    120.0.175.255

 

120.0.176.0        120.0.176.1 - 120.0.191.254                                   120.0.191.255

 

120.0.192.0        120.0.192.1 - 120.0.207.254                                   120.0.207.255

 

120.0.208.0        120.0.208.1 - 120.0.223.254                                   120.0.223.255

 

120.0.224.0        120.0.224.1 - 120.0.239.254                                   120.0.239.255

 

120.0.240.0        120.0.240.1 - 120.0.255.254                                   120.0.255.255