In Part 1 I wrote about DNS (Domain Name Servers). The ones that resolve the name of a domain it the actual Internet Address (eg: 126.96.36.199), the fact that by default you used the one in your WiFi router, and finally that choosing a different DNS Server may get you better performance when browsing.
But which DNS Server should you choose? Long ago an engineer at Google wondered this and built a tool called Namebench. The tool tested the speed of performing lookups from your machine to a list of known servers around the globe. You could use it to work out which server worked best for you right now.
The Computer Science Department at Northwestern University went one step further and created a tool called NameHelp. It was a modified version of Namebench to update your DNS settings periodically. It ran the Namebench tests and tweaked your DNS settings if something changed.
The speeds of DNS servers change over time depending on many networking factors, one of which is the speed from your machine to the distant server, general network congestion and availability of the servers - just the other day Amazons DNS service was down for several hours due to a DDoS attack. The closer the server, often the better. But not always. Cloudflare is further away than my Google Wifi Router DNS but is faster.
Which DNS Server you pick it up to you. Here are a few well known ones.
188.8.131.52 - Google 184.108.40.206 - Cloudflare 220.127.116.11 - UltraDNS 18.104.22.168 - OpenDNS
If you are going to pick one - or several - and you move around you should pick one that has lots of Points of Presence (POP). This means no matter where you are instead of just having the one DNS Server, they have lots of them scattered all over the country / planet. This is how Google's DNS works, and also CloudFlares. Cloudflare have 194 locations, Google has an unknown number. OpenDNS is now owned by Cisco and has servers in many countries but they have different IP addresses so less useful.
There are plenty of tools out there that you can use. I recently started using DNS Benchmark and DNSPerf is always worth checking.
Changing the DNS settings on your device are left as an exercise for the reader. On iOS you can change them per WiFi connection but not for your mobile connection.
In future posts I'll write about DNS Security, Time To Live (TIL), hosting your own DNS Server, a way of using Cloudflare's DNS for everything and the benefits of doing so