contact fb.com owner

and ask them why they only have two authoratative name servers for their domain where they risk downtime, if they are upgrading one and the second one crashes it would bring down fb.com. Ask them if they would like to zone transfer with [login to view URL] name (IP [login to view URL]) server for higher redundancy and quicker recovery and it is in different TLD .as andrzejs-air:~ andrzej$ dig [login to view URL] ns ; <<>> DiG 9.10.6 <<>> [login to view URL] ns ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 37721 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 5 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;fb.com. IN NS ;; ANSWER SECTION: fb.com. 172800 IN NS a.ns.facebook.com. fb.com. 172800 IN NS b.ns.facebook.com.