[beneills]

Or your user-agent is the same as one. Unless they are whitelisting IPs.

I tested this with: wget --user-agent "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)" http://www.facebook.com/robots.txt

and diffed, but the results are the same.

[phyalow]

Is your IP range the same as googles?

[tazzy531]

Google doesn't release their IP ranges. It can come from any IP.