Which domain name is returned on reverse lookup?
 

Here's one I haven't had any luck googling, probably because I don't know the right term to search for. I've got three different DNS records resolving to my DSL connection (static IP). One that my ISP automatically set up, one that I bought a while back that I'm using for a site, and one for my girlfriend's small (5 MB/month transfer) site that I'm hosting for her.

When I do a reverse lookup by entering my IP address, I always seem to get back the domain name that my ISP set up. How is it decided that this is the one that will be returned? Is there any way to change it? I'm mostly just curious because I can't figure out how this works. I'm pretty n00b at DNS stuff. :rolleyes:

Reverse lookups are answered from in.addr records set up by the owner of the address space. In these days of overloaded IPv4 space, with potentially tons of virtual sites at each address, reverse lookups are often wrong. Many hosting providers no longer maintain them beyond "company x hosting" or similar. With a hosting account at a single address you can probably get help having the records modified. If you're behind a residential connection or a hosting reseller it can be difficult or impossible to get provider support for in.addr changes at all.

Edit: Of course, can't hurt to ask!

Cool, thanks for the info. I don't really need to change it, I just wanted to know how the infrastructure was set up.

in-addr.arpa is the domain, and IPs are looked up in reverse. For an IP address such as 64.236.24.4, the DNS resolver looks up the name 4.24.236.64.in-addr.arpa to find out its reverse. IPv6 is done similarly, but with the domain ip6.arpa.