You have several options:
- Store it as a VARCHAR. IP address isn't really a number you're likely to do math on, so why store it in numeric format?
- Store it in hexidecimal as a single number. While you can't really do that in decimal, in hexidecimal an IP is an 8 digit number.
- Store it as (up to) four separate fields. Probably unnecessary but for certain applications (where you might want to primarily only be concerned with one part of the IP) this could be useful.
