Network - Domain Name System ( DNS )

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The Domain Name System (DNS) is a database of name. It's naming system (service).

It hold naming information for some kind of object (not only but mainly host)

DNS can be seen as the phone book of the internet:

An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer names into IP addresses.


For example:

This is called a DNS lookup (forward).


A DNS has the following major components:

Dns Architecture



You buy a apex domain to a provider that will also gives you access to their DNS server in order to manage the DNS record of your domain (called a DNS zone).

You may migrate them to third party. For instance, if you become CloudFlare customer, you need to design their DNS servers as the server of your domain.


see DNS - Record



A query against a DNS database is called a lookup

The two most known client are:


Locally, the DNS resolver will first check the host file



DNS - Cache


The DNS responds with a IP dependent of your location. This is used to build a cdn.


With GeoDNS:


With A DNS problem, don't forget to flush your DNS cache.

Documentation / Reference

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