AltF DomainOps

NS lookup: nameservers and DNS host

An NS lookup shows the authoritative nameservers for a domain, which tells you who controls its DNS: Cloudflare, Route 53, GoDaddy, Namecheap and so on. DomainOps names the DNS host from the hostnames and, in the Registration tab, shows the nameservers the registry has on file, which should match.

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  • Real DNS, RDAP and TLS data
  • Raw records shown
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Check a domain

Why the NS record matters

Whoever runs the nameservers decides every other record. If you edit DNS at a provider that is not in the NS list, nothing changes. After a migration, the NS set at the registrar is what switches traffic to the new host.

Healthy nameserver setup

  • At least two nameservers (most providers give four).
  • The registry's NS list matches the zone's own NS records.
  • Nameserver hostnames resolve, and are not on a domain that is about to expire.
  • SOA serial is the same on every nameserver after a change.

NS lookup: questions and answers

How do I check if my nameserver change worked?

Look up NS for the domain here and in the Registration tab. When the registry shows the new nameservers and Google and Cloudflare return them in Resolver compare, the change is live. Resolvers can hold the old NS set for up to its TTL, often 48 hours at the parent zone.

Can a domain have nameservers from two providers?

Yes, if both providers serve identical zones. It protects against one provider's outage but needs a sync process; most sites use a single managed provider with anycast.

Focused checks and guides

Checks

Full domain health checkAll nine tools, the record glossary and how each check works.DNS lookupFree DNS lookup for A, AAAA, CNAME, MX, NS, TXT, SOA, CAA, SRV, DS, DNSKEY and HTTPS records, with TTLs, DNSSEC status and what each record means.MX lookupFree MX record lookup: see a domain's mail servers in priority order, which email provider runs them, and whether SPF and DMARC are set.TXT record lookupFree TXT record lookup that labels each record: SPF, Google and Microsoft verification, Meta, Apple, Stripe and 25 more services, plus DMARC and DKIM.SSL certificate checkFree live SSL checker: connect to any site and see its certificate issuer, expiry date and days left, covered hostnames, chain trust and TLS version.Domain expiry checkCheck when a domain expires from the registry's own RDAP data: expiry date, days left, registrar, transfer lock and status codes in plain English.Reverse DNS lookupFree reverse DNS lookup for IPv4 and IPv6: find the PTR hostname of an IP address and the network owner from the regional internet registry.DNSSEC checkCheck whether a domain uses DNSSEC: DS record at the registry, DNSKEY in the zone and whether public resolvers validate the answers.CAA record checkLook up a domain's CAA records to see which certificate authorities may issue certificates, including wildcard and reporting rules, with fixes.

Guides

Domain launch checklistA 20-point checklist to launch a new domain: DNS records, www, HTTPS, email authentication, DNSSEC, CAA, registrar lock, with a free check for each step.Website migration DNS checklistMove a website or DNS to a new host without downtime: lower TTLs, copy records, switch nameservers, watch resolvers, handle DNSSEC and email.Email domain setup guideSet up email for your domain the right way: MX records, one SPF record under 10 lookups, DKIM keys, a DMARC rollout plan, MTA-STS and BIMI.

25 more free domain and DNS tools

Single-purpose AltFTool tools for one job each, grouped by what you are trying to do.

Lookups

One question, one answer.

Write records

Generate correct records before you paste them into your DNS host.

Certificates and HTTPS

Go deeper than the live certificate check.

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AltFTool does not store the domains or addresses you check. DNS lookups in the DNS, compare, email and IP tools run from your browser; registration, report and certificate checks pass through AltFTool's server and keep nothing.