NS Lookup
Find a domain's authoritative nameservers and SOA record, and identify the DNS provider.
What is an NS record?
An NS (Nameserver) record names the authoritative DNS servers for a domain — the servers that hold the real answers for everything else (A, MX, TXT, and so on). When a resolver wants any record for your domain, it first finds your NS records, then asks those servers directly.
NS records are set at two levels: at your registrar (in the parent zone, which is what the rest of the internet follows) and inside your own zone. They should match.
What is the SOA record?
The SOA (Start of Authority) record holds administrative metadata for the zone:
- MNAME — the primary (master) nameserver for the zone.
- RNAME — the responsible party's email address, written with a dot instead of the
@. - Serial — a version number, bumped on every change so secondary servers know to refresh.
- Refresh / Retry / Expire — timers governing how secondary nameservers sync from the primary.
- Minimum TTL — how long negative (NXDOMAIN) answers may be cached.
What this tool shows
- Every authoritative nameserver for the domain
- The IP address(es) each nameserver resolves to
- The full SOA record, field by field
- The DNS hosting provider detected from the nameserver hostnames
Common nameserver problems
Mismatched NS records
If the NS records at your registrar differ from the NS records inside your zone, resolvers can get inconsistent answers. They should be identical.
Too few nameservers
Best practice (and most registrars' requirement) is at least two nameservers, ideally on separate networks, so DNS keeps working if one goes down.
Lame delegation
A "lame" nameserver is one listed in NS records that doesn't actually answer authoritatively for the domain. It causes slow lookups and intermittent failures.
Frequently Asked Questions
How many nameservers should a domain have?
At least two, and most registrars require it. Managed DNS providers typically give you four or more, spread across different networks, so your DNS survives an outage of any single server.
What's the difference between NS records and my registrar?
Your registrar is where you bought the domain. The NS records tell the world which DNS servers are authoritative — those can be the registrar's own, or a separate DNS host like Cloudflare or Route 53. Changing NS records (delegation) is how you move DNS hosting without transferring the domain.
What does the SOA serial number mean?
It's a version counter for the zone. Many operators use the format YYYYMMDDnn (date plus a daily counter). Each time you edit the zone, the serial should increase so secondary nameservers know to pull the update.
How long do nameserver changes take?
NS delegation changes go through the TLD (e.g. .com) and can take anywhere from a few minutes to 48 hours to fully propagate, depending on the parent zone's TTL and resolver caching.
Why does my RNAME look like an email with no @?
The SOA RNAME field encodes the responsible party's email with the @ replaced by a dot — so [email protected] becomes hostmaster.example.com. It's a DNS formatting quirk, not a mistake.