It's not just periods. They're filtering out certain characters [.,-] hxxp://graph.facebook.com/-----r.-o....b....o-t-s-t....x....t----....///////////___%%20%

It's not just periods. They're filtering out certain characters [.,-] hxxp://graph.facebook.com/-----r.-o....b....o-t-s-t....x....t----....///////////___%%20%22/test/robots will still output the same result as http://graph.facebook.com/robotstxt http://graph.facebook.com/robotstxt