How to Find a Hostname behind an IP Address

In most cases, when your firewall blocks access to a remote system or maybe your spam filter traps a potential email attack, the only feedback you get about the source is an IP address.

However, since most individual or company computers connected to a network have private IP addresses, you can only discover their hostnames if the network has a local DNS Server. You can try using the Command line program nslookup in the TCP/IP networking protocol on windows but you have to be connected to the internet.

To find the domain name associated with a cryptic IP address such as ’77.73.187.122’, you will need to pass the address to any Domain Name System (DNS) server. You will require a windows utility to query the host itself.

Option 1: Querying DNS

Click the “Windows Start Button” then “All Programs” and “Accessories”. Click on “Command Prompt” from the list of Accessories and select “Run as Administrator”.
Insert “nslookup %ipaddress%” in the black box that pops up on the screen, replacing %ipaddress% with the IP address for which you want to find the hostname.
Find the line labeled “Name” underneath the line with the IP address you entered and record the value next to “Name” as the hostname of the computer.
Type “Exit” to close the command prompt window.

Option 2: Without DNS

Click the “Windows Start Button”, then “All Programs” and “Accessories”. Select “Command Prompt” from the list of Accessories and then click on “Run as Administrator”.
Type “nbtstat –A %ipaddress%” at the command prompt in the black window that opens, substituting the IP address for “%ipaddress%”
Review the results and find the NETBIOS table. Identify a row where the string is “UNIQUE” then find the hostname of the computer in the “Name” column for that row.
Type “Exit” to close the command prompt window.