Dig -x ...

$ dig -x 69.69.69.69

; <<>> DiG 9.4.2-P2 <<>> -x 69.69.69.69
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 17090
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

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

;; ANSWER SECTION:
69.69.69.69.in-addr.arpa. 86400 IN PTR the-coolest-ip-on-the-net.com.

;; AUTHORITY SECTION:
69.69.69.in-addr.arpa. 86400 IN NS dns1.utelfla.com.
69.69.69.in-addr.arpa. 86400 IN NS ns10.embarqservices.net.

;; ADDITIONAL SECTION:
dns1.utelfla.com. 60003 IN A 138.210.81.3
ns10.embarqservices.net. 43433 IN A 205.160.188.2

;; Query time: 338 msec
;; SERVER: 132.227.64.13#53(132.227.64.13)
;; WHEN: Fri Nov 28 14:17:51 2008
;; MSG SIZE  rcvd: 181

Par contre, 42.42.42.42 est décevante.

---

$man dig

DIG(1)                                                        BIND9                                                        DIG(1)

NAME
       dig - DNS lookup utility

SYNOPSIS
       dig [@server] [-b address] [-c class] [-f filename] [-k filename] [-p port#] [-q name] [-t type] [-x addr]
           [-y [hmac:]name:key] [-4] [-6] [name] [type] [class] [queryopt...]

       dig [-h]

       dig [global-queryopt...] [query...]

DESCRIPTION
       dig (domain information groper) is a flexible tool for interrogating DNS name servers. It performs DNS lookups and
       displays the answers that are returned from the name server(s) that were queried. Most DNS administrators use dig to
       troubleshoot DNS problems because of its flexibility, ease of use and clarity of output. Other lookup tools tend to have
       less functionality than dig.
[...]