gistfile1.txt

localhost:~ jamie$ dig @4.2.2.1 ptr 4.2.2.1

; <<>> DiG 9.8.3-P1 <<>> @4.2.2.1 ptr 4.2.2.1
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 27874
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;4.2.2.1.  		IN	PTR

;; AUTHORITY SECTION:
.			81334	IN	SOA	a.root-servers.net. nstld.verisign-grs.com. 2013041601 1800 900 604800 86400

;; Query time: 15 msec
;; SERVER: 4.2.2.1#53(4.2.2.1)
;; WHEN: Tue Apr 16 11:58:41 2013
;; MSG SIZE  rcvd: 100

localhost:~ jamie$ dig @4.2.2.1 ptr 1.2.2.4.in-addr.arpa

; <<>> DiG 9.8.3-P1 <<>> @4.2.2.1 ptr 1.2.2.4.in-addr.arpa
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 16637
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;1.2.2.4.in-addr.arpa.		IN	PTR

;; ANSWER SECTION:
1.2.2.4.in-addr.arpa.	40567	IN	PTR	a.resolvers.level3.net.

;; Query time: 4 msec
;; SERVER: 4.2.2.1#53(4.2.2.1)
;; WHEN: Tue Apr 16 11:58:50 2013
;; MSG SIZE  rcvd: 74

localhost:~ jamie$