What is a DNS?
A DNS, or Domain Name Service, translates human-readable names like google.com to numbers more suitable for computers to locate an actual machine on the network and talk to it.
Why should I care?
Every page loaded in your browser starts with a DNS request to locate the machine that hosts the website.
Whoever has access to your DNS account can render your application inaccessible to most users for all intended purposes.
How does it work?
There are different national organizations responsible for the top level-domains (.com, .org, etc.). In some cases, the jurisdiction, responsible for the top-level domain (ex: Colombia for .co domains) matters to keep your site accessible to users or verify the domain’s legal owner.
Once you have chosen a hosting platform and e-mail provider for your application, there is a one-time setup to add DNS records that point to the machine location that hosts your application.
A CDN or load-balancer is often the entry point to the application. As such, DNS records typically point there.