Does Facebook log my ip or my computer id?

This is a question ive always wanted to know, is there a way to tell which computer makes the accounts? or is it the ip address? reason I ask is because my friends all use my router on there iphone when the come into my house, however my IP is blocked my facebook from making accounts, yet if i make an account on a proxy and then login via my ip address it gets deleted 12 hours later, yet my friends personal accounts never get deleted even though there on the same ip?

yes, nowadays , facebook just limited only 3 new account created from same IP..

It is the IP address. FB, nor any other website (such as CL) can track you by your MAC address as far as I know.

IMHO, the reason the accounts you create on a proxy get deleted once you login to them with your real IP is because they are fake accounts and FB is very good and quick at detecting them these days. Your friends' accounts do not get deleted because they are actually real and established FB accounts. Real and established FB accounts go a long way these days.