This tool will resolve an IP Address to it's Reverse DNS Name or resolve a Hostname to a IP Address. This tool can be used to find the IP Address that a website is pointing to. This will also reverse lookup a Hostname your internet service providers has on your IP Address and give you the readable IP Address in digits.
A Reverse DNS Lookup or Reverse DNS Resolution (rDNS) is determining the domain name associated with a given IP Address.More information on Reverse DNS Lookup can be found on the Wikipedia page.
Reverse DNS Lookup: