NS lookup
Find out which nameservers answer for a domain. Look up its NS records live from a public resolver and confirm a DNS provider change took.
Related tools: DNS lookup · A record lookup · CNAME lookup · TXT record lookup · CAA record lookup · Reverse DNS lookup · DNS propagation checker · All free tools
Which servers are authoritative for a domain
NS records name the servers that hold a domain's zone: every other record for the domain is only as reachable as these. An NS lookup asks a resolver which nameservers a domain delegates to and returns their hostnames with a TTL. This tool sends that query to Cloudflare's 1.1.1.1 resolver over DNS-over-HTTPS from outside your network, which is the view the rest of the internet has of your delegation.
A delegation that changes without you knowing is how a domain gets hijacked, and how a registrar migration silently points the world at an empty zone. Upcheck checks every website's NS records every 6 hours and alerts your team when they change.
Three steps, no signup
- 01
Enter a domain
The registered domain, such as example.com. Subdomains usually inherit the parent's nameservers unless they are delegated separately.
- 02
We ask a public resolver
The NS query goes over DNS-over-HTTPS to Cloudflare's 1.1.1.1 from Cloudflare's network.
- 03
The nameservers come back
As hostnames with TTLs, so you can confirm a provider change and see how long old delegations may linger in caches.
Frequently asked questions
What is an NS record?
A nameserver record. It names a server that is authoritative for a zone, meaning it holds the real copy of the domain's records. The parent zone (the .com registry, say) publishes NS records for your domain so that resolvers know where to go, and your zone publishes the same set. When the two differ, resolvers may see either, which is the classic symptom of a half-finished provider change.
I changed nameservers at my registrar. Why does the lookup still show the old ones?
Delegation TTLs are long, often 48 hours, because the parent zone expects them to change rarely. Any resolver that looked up your domain recently keeps the old NS set until its TTL runs out. The registrar change itself can also take time to reach the registry. Check again later, and use the DNS propagation checker to see how many public resolvers have picked up the new delegation.
How many nameservers should a domain have?
At least two, on different networks, so that one outage doesn't take the domain down; most managed DNS providers give you two to four. More than that adds little. What matters more is that every listed nameserver actually serves the zone: a stale NS record pointing at a server that no longer knows your domain causes intermittent failures that are painful to diagnose.
What is the difference between NS lookup and nslookup?
nslookup is a command-line tool that can query any record type; an NS lookup is a query for NS records specifically. Running nslookup -type=NS example.com on your own machine gives the same kind of answer as this page, filtered through your local resolver's cache. This tool does it from outside your network, which is usually the view you actually want.
Is this NS lookup free?
Yes. No account, no limit on lookups by hand; scripted use is rate limited. Upcheck's monitoring re-checks every website's NS records every 6 hours as part of its DNS check and alerts your team when the delegation changes.
One lookup shows the delegation. Monitoring shows it moving.
Add your websites to Upcheck and get alerted by email, Slack, Discord, Teams, or webhook when nameservers change under you.