Domain Naming System (DNS) is a standard protocol by which human friendly domain names like facebook.com are translated to machine friendly IP addresses like 192.168.0.1
What does DNS tool do?
DNS tool queries a DNS server to fetch records for a given Domain or IP. This tool will fetch all types of DNS records. For a specific type of records use the Advanced DNS tool.
Which DNS server does this tool use?
It uses the local DNS by default. It is a non-caching DNS Server. If "Use domain name server" is checked, then it uses local DNS to fetch name servers for the domain and uses any one of the return name servers for the remaining query. Advanced DNS tool allows you to specific your own DNS server.
How does it work with IP addresses?
DNS works only with human friendly domain names like google.com. When a IP address is given, it does a reverse IP search to find the domain name registered with the IP and then queries records for that domain (if found).