DNS

Introduction

With more that 21.5 billion interconnected devices in 2021, how is the communication established among these devices one might ask. How does you device know how to reach the servers where this page is hosted.

Lets understand the stakeholders here, 1. Server (Gitbook) : Hosts contents of this page making it publically accessible. 2. DNS (Domain Name Server) : This public directory translating domain names to public locations (IPs, other domains as in our case). 3. Client : You the visitor, requesting this page. You request book.buggyweb.com, your devices asks the DNS to look in its records and reply with the public location of the server. In other words the DNS provider points the registered domain to the server hosting the page contents. This way the device knows the location of this site.

In the movie "The Terminator", protagonist uses Address Directory to find the home location of Sarah Connor

Authoritative Server:

If a server knows IP-host-name mappings of all hosts in a domain, then it is an Authoritative Server. For example, consider "mail.google.com". Here, the top level domain is "com" then "google.com" then "mail.google.com". The "mail" (server) is one of the hosts in "google.com" domain.

Now, an authoritative (DNS) server for "google.com" would know ip mappings for all hosts in the domain, i.e mapping for "mail.google.com" aswell.

Types of records