Hello everybody.
I am trying to do something simple.
I have an IP address and need to do a reverse DNS lookup.
However, I consistently get a "host not found" error.
I have tried this in at least 2 different machines.

What am I doing wrong?

nk@livaditis: ~ $ irb
irb(main):001:0> require 'socket'
=> true
irb(main):002:0> Socket.gethostbyaddr("75.126.252.65")
SocketError: host not found
        from (irb):2:in `gethostbyaddr'
        from (irb):2
        from :0