How To Resolve IP Addresses To Domain Names?

Yes, you can (sometimes) resolve an IP Address back to a hostname.

Within DNS, an IP Address can be stored against a PTR record. You can use nslookup to resolve both hostnames and IP addresses, though use of nslookup has been deprecated for quite some time.

For best results, you should really get a hold of the dig tool. If you're a linux user, this is available as part of dnsutils (debian), or similar package. If you're a windows user, you can follow instructions such as these to install dig.

You can then do:

dig A <hostname>

To lookup the IPv4 address for a host, or:

dig AAAA <hostname>

To lookup the IPv6 address for a host, or:

dig PTR ZZZ.YYY.XXX.WWW.in-addr.arpa.

To lookup the hostname for IPv4 address WWW.XXX.YYY.ZZZ (note the octets are reversed), or:

dig PTR b.a.9.8.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.

To get the hostname for the IPv6 address 2001:db8::567:89ab.

nslookup <ipaddress> or nslookup <hostname>

You can use nslookup, dig, or other network tool to possibly get a domain name for an IP address, but it's not necessarily going to be the one you're expecting.

Unlike normal DNS lookups, where many names can resolve to a single IP address, reverse DNS lookups can only resolve to a single name, and that's handled by whomever controls the reverse DNS information for the IP block in question. Nobody else can set up a PTR record on a random IP address block. This is in contrast to "normal" DNS lookups, where anyone can set up a domain name and create A records pointing at whatever IP addresses they'd like.

This ServerFault question has a bit more info on this topic.

My point is that just because you can do it doesn't mean that you'll get what you're expecting or that it will be useful.