IPNetInfo is a free small utility which allows you to easily find all available information about an IP address: The owner of the IP address, the country/state name, IP addresses range, contact information (address, phone, fax, and email), and more.

IPNetInfo can be very useful for finding the origin of unsolicited mail. You can simply copy the message headers from your email software and paste them into IPNetInfo utility. IPNetInfo automatically extracts all IP addresses from the message headers, and displays the information about these IP addresses.

How does IPNetInfo work ?

The IP address information is retrieved by sending a request to the whois server of ARIN. If ARIN doesn’t maintain the information about the requested IP address, a second request is sent to the whois server of RIPE, APNIC, LACNIC or AfriNIC.
After the IP address information is retrieved, IPNetInfo analyzes the Whois record and displays it in a table.

Notice: From time to time, the WHOIS server of ARIN is down and doesn’t respond to WHOIS requests from IPNetInfo, and thus IPNetinfo fails to retrieve the IP address. When such a thing occurs, simply try again later.

Version 1.95 Update：
You can now change all settings from command-line, by using the same variable like in the .cfg file, for example:
IPNetInfo.exe /AutoFailedRetry 1 /AllowIPv6 0
System Requirements:
1.Windows operating system: Any version of Windows, starting from Windows 98 and up to Windows 10.
2.Internet connection.
3.On a firewall, you should allow outgoing connections to port 43.