The Root and Top-Level Nameservers

I was reading: Web Security, Privacy & Commerce by Simson Garfinkel and it was interesting to know that there are only 13 DNS root servers on the internet that are responsible for resolving the IP addresses to the top level domains (e.g: .com, .org, .net). For example, when you write unesco.org on the address bar of your browser, the address will be resolved from right to left. The client computer will ask one of these 13 root servers to resolve the address of .org server which accordingly will be responsible to fetch the address of the unesco.org. The address formats of the root servers is: X.ROOT-SERVERS.NET where X ranges from A to M.

You may have an initial guess that most of these servers exist in the United States. But actually this not correct. Most of the physical root-servers are outside the United States and distributed in multiple locations in different continents. Check the full list here: root-servers.org

The root-servers are completely transparent to the internet users. It's the hidden side of the internet. They are definitely critical zones in the network. This is why they are carefully watched and monitored. As the whole traffic depends on these 13 servers, any crash or unexpected behavior happened in these servers, the internet users will have to memorize the IP addresses to be able to navigate on the internet. Needless to mention that any referral, ads or even bookmarks will be unreachable without the existence of these 13 servers.