Domain Name System (DNS)
- Standard term
The Domain Name System (DNS) is the internet's distributed directory for domain names. It stores records saying where a name's website and email go, which values prove ownership, and which servers answer for the name.
When someone types your address, their device asks a resolver, a lookup service often run by their internet provider. The resolver asks your domain's name servers, the servers that hold its records, then keeps the answer for a set time called its TTL (time to live). So a change can take hours to reach everyone.
Where you’ll meet it
Your website host's setup page tells you to add two records “at your DNS provider.” You add them at the company where you bought your shop's domain. A day later, the address still opens the old site.
What to do
The company that sold you a domain doesn't always run its name servers. Ask your AI to look up your domain's name servers and tell you which company runs them. Add the two records there, then check that the site opens with and without www.
Easy to mix up
| Domain Name System (DNS) | Domain name |
|---|---|
| No, it's a shared system that holds your records | Yes, it's registered to you while you keep renewing |
Check yourself
To move your website, you follow the new host's guide and switch your domain's name servers to theirs, and the host sets up the website's records for you. The site works, but by evening email to your business address bounces. What is the likely cause?
Go deeperLookups start at the root, and lowering the TTL speeds a switch
Paul Mockapetris designed DNS in 1983 to replace a single shared file that listed every early internet host. A lookup runs down a chain of delegation. Root servers point to the servers for .com, and those point to whichever name servers the domain's registrar, the company it was bought from, has on file. Those last, “authoritative” servers give the final answer.
Some resolvers hold an answer past its TTL. A planned switch still goes faster if you lower the TTL to a few minutes a day ahead, so saved copies expire soon after the change. After a change, compare what the authoritative servers return with what public resolvers return before treating a slow update as a failed one.