Glossary / NS record

NS record (name server record)

An NS record (name server) says which DNS servers are responsible for a domain's zone - that is, where all of its records actually live. NS tells the internet whom to ask about this domain's A, MX, and TXT. They decide who controls your site's DNS.

When you register a domain, the registrar sets NS records like ns1.tomishost.com and ns2.tomishost.com. This is delegation: the top-level registry says "these servers are responsible for this domain," and from then on every query goes to them.

Changing NS means handing DNS control to another provider - a host, Cloudflare, or a dedicated DNS service. After the change, all of the domain's records come from the new pair of servers, and the old ones stop counting.

There are always at least two NS records, for reliability. If they point the wrong way or clash with what the registrar has, the domain's DNS behaves erratically: part of the world sees old records, part sees new ones.

Example

example.com.  86400  IN  NS  ns1.tomishost.com.

Common mistakes

• Confusing the NS at the registrar with the NS inside the zone; the registrar's are what actually delegate the domain.
• Changing NS and expecting an instant effect; delegation can take up to a day because of a high TTL.
• Leaving an old, dead server among the NS, so some queries get stale answers.
• Assuming an NS switch carries the old records over; the new DNS needs the zone filled in from scratch.

Related terms

• A record A record (DNS address record)
• AAAA record AAAA record (DNS IPv6 record)
• CNAME record CNAME record (DNS alias)
• MX record MX record (mail exchanger)
• TXT record TXT record (DNS text record)