Yes indeed, reverse DNS lookps are a fairly common thing to want to
do, and numerous programs exist for all manner of operating systems.
There are even websites setup to do reverse DNS lookups for you.
If you have a plain text file with IP numbers in it, you can use an
application called QuickDNS (
http://www.analogx.com/contents/download/network/qdns.htm ). It comes
with a license that looks like it was ripped off some commercial app
or other, but is a free-to-use program.
Download the application and run the installer. The program is a
command-line program, but can be run from the GUI if you prefer. The
help file explains the options, but you will almost certainly be
interested in a command line like:
qdns -D c:\web\DNS.txt -L c:\web\list.of.IPs.txt -Y your.favorite.DNS server
That will use your favorite DNS server to lookup the IPs listed in
list.of.IPs.txt and will make entries in DNS.txt, one per line, with
the IP number and the associated domain name. If run several times,
it uses the DNS.txt file to cache entries so it only needs to lookup
new IPs. There are options for ageing entries in this file as you'd
like, if this is a useful or necessary feature for you.
I have tested this program and command line options on a plain text
file with one IP per line. Not all IPs have reverse DNS entries (even
if they do have associated DNS names), but with that proviso, the app
ran as advertised.