DNS lookup

Check which name servers are authoritative for a domain

NS records name the servers that hold the official copy of a domain's zone. Every other record you look up comes from these servers.

What the NS record shows

The registrar stores the NS list for the domain, and the zone publishes the same list. When the two lists differ, some resolvers use the old servers and the domain behaves differently for different visitors.

Two or more name servers in different networks keep the domain online when one of them fails. Host names usually reveal the DNS provider, for example ns1.cloudflare.com.

When you need it

Check the switch to a new DNS provider or registrar
Find out who manages the DNS of a domain before you ask for a change
Diagnose a site that opens for some users and not for others after a move

Questions about DNS records

01How long does a name server change take?

Up to 48 hours. The registry caches the delegation for a long time, and resolvers keep the old NS records until that cache expires.

02Is one name server enough?

No. If it fails, the whole domain stops resolving. Registrars ask for at least two servers.

03Where do I change NS records?

At the registrar of the domain. The DNS provider shows the server names to enter there.

04Why do the NS records at the registrar and in the zone differ?

The registrar keeps the delegation in the registry, and the zone holds its own NS list. After a move to another DNS provider old NS records often stay in the zone. Fix them, or some resolvers will ask the wrong servers.

05What are glue records?

Addresses of the name servers stored in the registry. You need them when a name server sits inside its own domain, such as ns1.example.com for example.com: without glue a resolver cannot learn its address.