Reverse DNS Lookup

Communications on the Internet are done between IP addresses. An IP address is just a number that is used as an identity, and is used to get to a particular computer or facility (thus, it's an address). When an IP address is presented for a human to read, it's usually punctuated in a way that makes it a little easier for the person to grasp. But fundamentally it's just a number.
Normally you don't deal with IP addresses-- you deal with names (called "host names"). Names are again a convenience for humans. When you access a host name, e.g. www.lognalyzer.net, the program that you are using translates that name to its corresponding IP address (a number), and communication ensues. This translation is done via the Domain Name System (DNS), the translation being referred to as a "DNS Lookup."

Sometimes it's necessary to find out what host name is associated with an IP address. There is a provision in the DNS for this kind of lookup, and since it's the opposite of the usual name-to-address translation, it's referred to as a "reverse DNS lookup."

Back To Tips of Web Log Analysis