This field should be set to the IP Address of this Server. If you do not already have TCP/IP on your network you should not need to change this field as the default value and mode of operation will ensure that all your PC's should be assigned matching values.
When computers use TCP/IP to talk to each other, they address each other using a unique IP Address. The way this works is that when you ask for a computer by name (e.g. a web site such as www.yahoo.com) the first thing that happens is that your PC will translate that name into an IP Address, (e.g, 216.32.74.52 ). The IP address is therefore a little bit like a phone number.
The default values for this field is "10.10.10.1"