How to block facebook by IPs?

[z3r0aCc3Ss]

Its kind of very difficult for me to block facebook by IP.
It uses so many IPs that its not feasible to block each and every IP.
Even if you block domain name from hosts file, it doesn't work when you access by IP.

There is one way by which I can block it by using NetNanny or sort of softwares.
But anybody knows how facebook uses different IPs and how to block it?

[DNR]

http://www.robtex.com/dns/facebook.com.html#shared" onclick="window.open(this.href);return false;

DNR