Double-click the Internal Subnet element.
The Configure Subnet dialog box appears.
Type the name of the Internal Subnet in the Name field.
Type notes or comments into the Notes field.
(Optional) Click the Add Host Name button to reserve a name for the IP.
Type the DNS name in the field provided.
This DNS name specifies the corresponding DNS prefix for each IP address that you reserve.
Click OK to save your changes.
The Configure Subnet dialog box is closed.