If you have unix or linux, you can do this by typing on a command prompt:
dig -x xx.yy.zz.aa
You'll get an answer with your authority of aa.zz.yy.xx.in-addr.arpa and server resolving to this address.
In windows you can do nslookup xx.yy.zz.aa
You can also check online at www.intodns.com and input your domain... it will error on the results checking for a reverse zone lookup.
xx.yy.zz.aa = The IP address you're trying to resolve
When using dig, nslookup, or host it is frequently useful to use a DNS server outside of your control like Google (184.108.40.206) so you get confirmation things are right from a 3rd party. – Zoredache
Zoredache makes a good point, here are the commands for testing/resolving to external/outside DNS servers:
Dig (testing reverse dns on Google's DNS server of 220.127.116.11):
dig -x zz.yy.xx.aa @18.104.22.168
Host and Nslookup (testing reverse dns on Google's DNS server of 22.214.171.124)
nslookup zz.yy.xx.aa 126.96.36.199
host zz.yy.xx.aa 188.8.131.52