Creating a top-level address entry

You must first define the top-level address that you want to subnet. The top-level address is derived from the network address and the network address length (mask length) in bits, supplied to you by your ISP or a NIC. The top-level address is also known as the IP prefix. See ``Subnetting and Classless Interdomain Routing'' for more details.

To create an address:

1. Select Edit Add Address.

2. Enter your network address in dotted decimal notation, for example, 195.34.136.0.

3. Select the network address length in bits, for example, /22. This is also known as the mask length.

   Depending on what type of network address you enter, the network address length is automatically assigned a length in bits according to whether it is a class A, B or C address. You can use the spin buttons to select the correct network address length.

4. Click on OK.