What this tool does
Nameservers (NS records) are the servers that hold a domain's authoritative DNS. This lookup lists them so you can confirm your domain points at the right DNS provider, spot a partial migration, or check redundancy. Two or more nameservers across different providers is healthy; a single one is a single point of failure.
Delegation, glue, and migrations
The nameservers the registry has on file (the delegation) should match the NS records the zone itself publishes. When they don't, you get a lame delegation that resolves intermittently and is maddening to debug. Glue records are the nameserver IP addresses stored at the parent when the nameservers live inside the same domain, which prevents a chicken-and-egg lookup. During a provider migration, expect NS changes to take up to 24 to 48 hours to fully propagate as the parent zone's TTL expires, and keep the old DNS answering the whole time.
Frequently asked questions
How many nameservers should a domain have?
At least two, and ideally on diverse infrastructure. Most registrars and DNS providers give you several by default so that a single outage doesn't take your domain offline.
Why did my nameservers change?
Nameserver changes happen when you move DNS providers or registrars. An unexpected change can indicate a misconfiguration or, rarely, a domain hijack, so they're worth monitoring.
Are these the same as the registrar's nameservers?
Usually, but not always. The registry publishes the delegated nameservers; this tool reads what DNS actually returns, which is what resolvers use.
How long do nameserver changes take to propagate?
Typically up to 24 to 48 hours. The delay is governed by the TTL on the parent zone's delegation, which is often a day or two, so resolvers keep using the old nameservers until it expires. Always leave the previous DNS provider serving your records until the change has fully propagated everywhere.