Online NSLookup

The nslookup command can be used in Windows and Unix to find the IP addresses of a particular computer, using DNS lookup. The name means "name server lookup". The most common version of the program is included as part of the BIND package. A more modern alternative to nslookup is the dig program, also shipping with BIND.
Source: WikiPedia

Take a look at our DIG tool for more DNS lookup options!