Why do you want the fastest DNS servers listed as DNS forwarders on your domain name server? Mainly, to get your internet experience to speed up. Having slow DNS forwarders can affect how long a browser takes to find and load a web page or to start downloading a file. In bad cases I’ve seen some sites become inaccessible because of bad DNS forwarders. Major sites like Google.com and Yahoo.com were getting “Page cannot be found” errors for an entire office!
There’s a quick way to figure which forwarders to set on your server. First, use a DNS benchmark utility. I’ve been using DNSBench and it’s served me well. It’s a free utility that test numerous DNS servers from your location so you can find and use the fastest ones for your computer and network. Even within a city like San Francisco, different locations will get the best results with different forwarders even inside the same building.
Download it from here. It’s self contained so you don’t have to install it, just put it in its own directory somewhere on your computer or external drive and run it. Click on Run Benchmark and wait. It’s best not use the PC as much as you can so it can test the DNS servers better and give you a more accurate result.
Once you get the fastest two or three identified, you can put those as your forwarders on your DNS server. Here is a screenshot of one of my DNS servers forwarders page. I set the priority based on the speed results I got from my DNSBench results. You can get by with 2 or 3 but as you can see from my screenshot, you can put more. You’ll notice that even DNS servers provided by the same companies can have differing speeds. After setting this up for one of my clients and changing the forward queries time out to 1 second – which you have to be careful of because slow internet plus short timeouts can result in the forward query loop because you’re not giving enough time for the request to go out and come back – internet surfing drastically improved.
Hope this helps.