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:
- it permits to get IP adress from names
- it connects email addresses to the right servers
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.
- the domain name www.example.com
- translates to the addresses:
This is called a DNS lookup (forward).
A DNS has the following major components:
- domain name space that defines a tree structure of name
- resources record that defined data associated with the names.
- name servers are server programs which hold information:
- about the domain tree's structure
- resolver. they are programs that extract information from name servers in response to client requests.
- the registrar controls the nameserver (This is where you can update the ns record)
- record (A, AAAA,…)
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
- The NS record, see server check
The DNS responds with a IP dependent of your location. This is used to build a cdn.
- https://dyn.com/ (Pricey ?)
- https://ns1.com/ (used by Jsdeliver)
- Cloud DNS (used by Jsdeliver as second DNS)
With A DNS problem, don't forget to flush your DNS cache.