DNS, or “Domain Name System,” is a technical system that essentially allows you to direct a domain name to which server it should lead you when you access it through various possibilities (main domain, subdomain, email system, etc.).
A domain name has an associated DNS server that contains the DNS records for that domain. There are different types of records with various uses; the most common are:
- Type A or AAAA: Indicate the IP addresses to which the request should go.
- Type CNAME: Indicate a subdomain or external domain to which the request should go.
- Type MX: Indicate the subdomain or external domain to which incoming email requests should go.
- Type TXT: Used to associate information with the domain, as is done with some verification or security systems.
It is common to talk about DNS when, for example, we perform a web server migration for a website; it is necessary to make changes in this system so that the domain correctly directs us to the new web server.
The DNS system operates on distributed and hierarchical systems that must synchronize their information. This is why a change to the DNS server associated with a domain usually takes between 4-8 hours, although it could take 24-48 hours. However, a change to a DNS record can be instantaneous for most systems, but may take some time for systems that have recently accessed that record (this is due to the TTL configured in the record, which causes that record to be stored for a determined period in the requesting system).