NS record delegates a DNS zone to a specific set of authoritative nameservers. Every zone must have at least one NS record set at its apex; delegations to child zones are also expressed as NS records.
Record Format
example.com. NS ns1.example.com.
example.com. NS ns2.example.com.Where NS Records Live
Two places — a subtle but important distinction:
- In the parent zone — the delegation. For
example.com, this lives in the.comzone at Verisign. When you configure nameservers in your registrar UI, you’re modifying the parent NS records. - In the child zone itself — the authoritative statement. Same nameservers, but published inside the delegated zone.
The parent and child should agree. When they don’t (lame delegation), some resolvers get confused.
Subdomain Delegation
You can delegate a subdomain to different nameservers by publishing NS records at the subdomain apex inside the parent zone:
blog.example.com. NS ns.blog-provider.com.Now blog.example.com is a separate zone hosted elsewhere.
Minimum Count
Best practice: at least 2 NS records with geographically diverse authoritative nameservers. Registrars typically require 2, some require the servers on different /24 networks for resilience.
Related
Check the nameserver glossary entry, the SOA glossary entry, and the glue record entry.