Так я про обратное преобразование, например:
mamon@mamon-desktop:~$ dig 3.134.158.93.in-addr.arpa PTR
; <<>> DiG 9.7.1-P2 <<>> 3.134.158.93.in-addr.arpa PTR
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55593
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;3.134.158.93.in-addr.arpa. IN PTR
;; ANSWER SECTION:
3.134.158.93.in-addr.arpa. 14180 IN PTR www.yandex.ru.
;; Query time: 1 msec
;; SERVER: 172.16.1.1#53(172.16.1.1)
;; WHEN: Tue Jan 18 13:34:05 2011
;; MSG SIZE rcvd: 70