A reverse DNS lookup is an online service commonly used to find out information pertaining to the ownership and registration of a web site, or the origin of specific web traffic that is arriving via a certain IP address. The difference between a regular DNS lookup and a reverse DNS lookup is that a reverse lookup is conducted by using an IP address, while a regular lookup is done using the web address of a site.
Reverse lookups are frequently used to find out the origin of spam and or excessive fake web traffic, in order to report this abuse to the web hosting company. After the spam attack or attempted DDoS attack has been logged in your web server's analytics you can use the IP addresses to lookup the origin of the traffic and then report the abuse to the appropriate authority, including the web hosting provider.
