FastResolver is a free tool that allows you to resolve IP addresses very quickly. The utility can also translate host names to IP addresses and retrieve MAC addresses.
Latest posts by Michael Pietroforte (see all)

FastResolver is another portable NirSoft tool that is quite simple but can also be very useful in some situations. You can either resolve a range of IP addresses or provide a list of IP addresses.

The latter feature can be helpful if your firewall or web server doesn't log domain names because of performance reasons. FastResolver is a multithreaded application, which makes it very quick.

Resolve IP Addresses - FastResolver Results

FastResolver can also do the opposite; that is, you can use the tool to resolve IP addresses to host names. This also works if a host has multiple IP addresses. And if an IP address has multiple host names, FastResolver can display those too.

Resolve IP Addresses - FastResolver - Select hosts IP addresses

The tool also allows you to quickly retrieve a list of the MAC addresses of the computers in your network, which you can use for Wake-on-LAN or resolve IP address conflicts (for instance). If you copy this text file as oui.txt into the FastResolver folder, you can also see the manufacturer of the networks card.

Resolve IP Addresses - FastResolver - HTML Report

Selected results can be saved to a text file, and you can display the output in an HTML page. As with most NirSoft tools, FastResolver also works on the command prompt, which can be useful if you have to resolve IP addresses in scripts.


  1. Avatar
    Bill Hart 7 years ago

    This article is 5 years old however I’m trying to craft a script using this tool to dump the local subnet to the hosts file.

    I have a WiFi network and printer managed by HQ and cannot modify any settings. I need to have computers print to DHCP assigned printers.

    These printers are wireless as well but when their IP changes we have to update all the clients manually.  If I could script this to dump the contents to the hosts file then I can bypass updating all the clients permanently.

    When I run this from the command line it opened up the GUI.

    Any idea how to get this to dump to  STDOUT?

  2. Avatar Author

    Does the tool also launch the GUI when you add one of the parameters? And by the way, why don’t you work with DNS to access the printers? It sounds odd what you are trying to do.

  3. Avatar
    Bill Hart 7 years ago

    It is odd. We have no access to the Wireless controller. This is a fortune 500 company with ultimate control over all networking equipment. I tried to create a ticket to change these things and it took 4 months to get a response. The answer was no.

    Yes, the GUI launches with command line args.

    For example:

    FastResolver /IPFrom /IPTo /GetMACAddresses 1


    Will launch the GUI. I’m scratching my head here. I essentially need a rogue WINS server for just two hosts.

    • Avatar Author

      Tried it now. You are right, the tool always opens the GUI.

      The interesting question is if your DHCP registers the IPs in DNS. If not, then should complain about this.

      I wonder what you are trying to accomplish? You want to know the current IPs of the printers using their MAC addresses?

      Then you can just run arp -a on a command prompt and get the MAC address of the printer. With the little PowerShell script below you can then get the current IP for the MAC address stored in the $mac variable:

      $mac = 'd0-22-be-3d-99-1d'
      $line = arp -a | select-string $mac | out-string
      $line = $line.trim()
      $ip = $line.Split(" ")[0]

  4. Avatar
    Bill Hart 7 years ago

    That’s gonna work.

    I just need to update the hosts file and generalize the code to take the MAC addresses/Hostnames via command line.


    When I get it tested and working I’ll post my results.

    Thanks for the code.

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