Do you mean an input mask? I never remember the exact rules for IP addresses, but if you remind me I can help you design one. What are the possible lengths of each part?
You will need to store the periods, so you will have to use the \ operator.
If the first group must be three digits, and the next three sections can be two or three characters, then the input mask would be:
000\.900\.900\.900
0 is the place holder for a required digit, and 9 is the placeholder for an optional digit.
Check out the Input Mask Property in the Help file.
Hope this helps. Kathryn