Mar 23rd, 2008

Hi Experts,

can anybody explain what is the difference between subnet & mask

Router#sh ip route connected

10.0.x.x/x is variably subnetted, 11 subnets, 5 masks

C 10.4.8.24/30 is directly connected, Serial0/0/0:0

C 10.4.8.25/32 is directly connected, Serial0/0/0:0

C 10.4.8.60/30 is directly connected, FastEthernet0/1

C 10.5.3.0/25 is directly connected, FastEthernet0/0.15

C 10.5.2.0/24 is directly connected, FastEthernet0/0.14

C 10.5.1.0/25 is directly connected, FastEthernet0/0.12

Regards,

Naidu.

Overall Rating: 5 (1 ratings)

## Replies

Justin Brenton Sun, 03/23/2008 - 23:05

Hello Naidu

A subnet is basically a network divided or split up into there own individual networks. For example a typical Class C private network 192.168.0.0 you can have 192.168.1.0 and 192.168.2.0. Each would be a separate network.

A mask is how you determine the size of the network, and where the network starts, i.e. 10.X.X.0 the ending 0 will indicate it's a network.

a mask for example will let you know how many host and networks you can use with that network mask, for example. if you have a IP address of 10.4.8.24/30 then the /30 means that you have 30 network bits. Their are 32 bits in a ip address or network mask. 11111111.11111111.11111111.11111100 or 255.255.255.252 Notice how there a 2 0's at the end. These are your host bits.

To figure out how many hosts you can have connected per subnetwork you would use the formula 2 to the power of X. In this example it would be 2 to the power of 2 - 2 . Which equals 2. In this example you would have a mask of 255.255.255.252. You can figure out the mask by using binary.

HTH

Regards,

Justin