You can add IP addresses when you add scopes and you can add them to existing scopes. IP addresses are allocated from scopes when IP-based sites are created. Scopes and IP addresses are not used when name-based sites are created. If an IP address range is full, however, no additional IP addresses can be added.
To add IP addresses to existing scopes:
On the top navigation bar, click administration, then click the IP addresses tab. Select a scope, then click list addresses.
A maximum of 256 IP addresses can be added to a scope.