DNS NS Record: Name Server Delegation Explained
A DNS NS (name server) record declares which servers are authoritative for a zone — that is, which name servers hold the real DNS records for a domain and are allowed to answer for it. NS records are how the internet's distributed DNS knows where to send queries for example.com instead of guessing.
What is an NS record?
Defined in RFC 1035, NS records perform delegation. When you register a domain, the registry (the operator of the .com, .org, etc. zone) stores NS records that point at your DNS provider's name servers. Those name servers, in turn, publish their own NS records at the zone apex. A resolver follows this chain — root → TLD → your name servers — until it reaches a server that can authoritatively answer for the name.
NS record structure and example
A zone normally lists two or more NS records for redundancy:
example.com. 172800 IN NS ns1.example-dns.com.
example.com. 172800 IN NS ns2.example-dns.com.| Field | Meaning |
|---|---|
| Zone name | The domain (or sub-zone) being delegated, e.g. example.com. |
| TTL | How long the delegation is cached. NS records commonly use a long TTL such as 172800 seconds (2 days) because name servers rarely change. |
| Type | Always NS. |
| Target | The hostname of an authoritative name server for the zone. |
When the name server's hostname is itself inside the delegated zone (for example ns1.example.com serving example.com), the parent zone also stores a glue record — the name server's IP address — to break the otherwise circular lookup.
How to check a domain's NS records
# dig (Linux/macOS)
dig example.com NS +short
# nslookup (Windows/cross-platform)
nslookup -type=NS example.comTo view a domain's NS records together with its SOA, address, and mail records at a glance, run it through the free DNS lookup tool.
NS records vs the SOA record
Both sit at the zone apex, but they answer different questions. The SOA record names the single primary source of the zone and its refresh timers. NS records list all the authoritative servers — primary and secondaries — that clients may query. A healthy zone has one SOA record and at least two NS records.
Common NS record problems
- Delegation mismatch. If the NS records at the registrar (parent) differ from the NS records published in the zone itself (child), resolvers can behave inconsistently. The two sets should agree.
- Only one name server. A single NS record is a single point of failure; if that server is unreachable, the whole domain goes dark. Use at least two on separate infrastructure.
- Missing glue. When name servers live inside the domain they serve, forgetting the glue record at the parent creates a lookup loop and the domain fails to resolve.
- Lame delegation. An NS record points at a server that is not actually configured to answer for the zone, so some queries silently fail.
Related DNS records
NS records sit at the top of a zone alongside the SOA record. Once queries reach your authoritative servers, the actual answers come from records like AAAA (IPv6 addresses) and PTR (reverse lookups).
Frequently asked questions
How many NS records should a domain have?
At least two, ideally on independent networks, so the domain stays resolvable if one name server fails. Many providers supply four or more.
What is the difference between NS records and glue records?
An NS record gives the hostname of a name server. A glue record supplies that name server's IP address at the parent zone, which is needed only when the name server's hostname is inside the zone it serves.
Do NS records affect my website's uptime?
Indirectly but critically. If your NS records are wrong or all your name servers are down, resolvers cannot find any of your other records, and the domain becomes unreachable even if the web server is fine.