Reverse DNS Lookup Tools | The Coffeehouse

W3bbo
The Master of Baiters

'lo

Does anyone know of any tools that do a reverse DNS of an IP address and list all the other domain names with an "A" record or NS entry pointing to that address? (That doesn't charge $20 a month)

Cheers

Maurits
AKA Matthew van Eerde

What you ask is not possible. All reverse lookup does is:

take the IP address
   10.1.2.3 (for example)

reverse it
   3.2.1.10

append the special domain in-addr.arpa
   3.2.1.10.in-addr.arpa

perform a forward lookup on that with type=PTR

in-addr.arpa is subdivided to the world's ISPs

If you have a class C (say) from your ISP, you can ask that they delegate the reverse ip address lookup zone to your DNS servers, in which case you control those in-addr.arpa PTR records.

Mike Dimmick

I wouldn't say it's impossible, but it is very hard. As Maurits implies, there's only one reverse mapping through PTR records from IP address to DNS name - this name can be considered a canonical name for the address. My employer's external address is nn-nn-nn-nn.dsl.isp.net.uk, where nn-nn-nn-nn is the IP address with '.' replaced by '-'.

There are currently at least four DNS names, which are mostly in completely unrelated domains, which point to that address. (It's actually the external address of a NAT firewall, which maps different services to different internal boxes).

The only way you can actually do it is to search DNS. That's hard, because many DNS servers do not permit a zone transfer - a dump of all records in the domain. In fact I think it's now quite rare to permit this as obviously it gives an attacker an entry point.

Loadsgood
What is your answer?

W3bbo wrote:
'lo

Does anyone know of any tools that do a reverse DNS of an IP address and list all the other domain names with an "A" record or NS entry pointing to that address? (That doesn't charge $20 a month)

Cheers

I use http://www.dnsstuff.com/ for all my DNS needs.

Don't tell me you've forgotten your IP address already Wink