Today’s Incident of Facebook not opening in India made one thing clear: You cannot rely on default DNS of your ISP. Following ISPs were observed to block Facebook:
Earlier, Indian Govt had requested Facebook and Google to screen the content. This time, No Public statement was released, but it was observed nationwide, but yes things were back to normal in a couple of hours!
What is DNS?
DNS means Domain Name System. The DNS Servers are primarily responsible for query translation. With a vast no of websites being registered everyday and IP addresses are difficult to remember, the concept of DNS came into being. Basically DNS server resolves the domain queries to IP addresses.
Why Public DNS?
Whenever you type a website name onto address bar, the query first goes to your DNS Server at ISP which are often unreliable and slow. There are many more faster superior Public DNS available and you should choose one of them. Here is great step-by-step tutorial to change your DNS on Windows/Linux/Mac/Mobile (Linux Users: Still reading, really?).
After changing DNS, make sure you flush your DNS resolver cache and web browser caches to ensure that your new DNS configuration settings take immediate effect.
Performance Issues with CDN?
Content Delivery Networks (CDNs) use a Global Load Balancing Technology. They use DNS Tricks and redirecting to the nearest server, basically using DNS Dynamically. DNS was never meant for this purpose.
Using the IP source address of a DNS request, the CDNs locate the source of requests geographically. Now based on the factors like Load on each Content Delivery Network Server, Network Traffic / Load and Proximity to the request origin, a DNS response is crafted to direct that source to the closest or best content server for that URI domain.
Simply speaking, If you use a Public DNS based at USA, High chances you will be served using a CDN server at USA and not the one at Asia, thus increasing the Latency. Read more about Impact of third-party DNS on CDN here. In short OpenDNS is enemy of CDNs.
List of Free Public DNS
- Google Public DNS (Fastest & Recommended)
- SmartViper Public DNS
- 207.225. 209.66
- Level 3 DNS (GTEI DNS, now Verizon) Update: Level 3 hijacking failed DNS requests
- 126.96.36.199 (most famous)
- 188.8.131.52 (security)
- 184.108.40.206 (security)
- 220.127.116.11 (security + pornography)
- 18.104.22.168 (security + pornography)
- 22.214.171.124 (security + pornography + non-family friendly)
- 126.96.36.199 (security + pornography + non-family friendly)
- DNS Advantage
Were you using the default DNS till now? Which one are you planning to switch to? Do share with us in the comments!