Registrar vs authoritative DNS host

• Registrar: where the domain was bought and is renewed. It tells the registry which nameservers the domain uses.
• DNS host (authoritative DNS): the company running those nameservers. Its dashboard is the only place record changes take effect.
• Web host: where the website or app runs. DNS records point at it; it has no say over them unless it is also the DNS host.

A domain bought at one company commonly has its DNS at Cloudflare, Route 53 or its web host. The registrar's dashboard usually still shows a DNS editor, which edits a zone that no resolver ever asks.

A customer adds the record you asked for, waits a day, and nothing happens. Often they added it at the registrar while the domain is delegated elsewhere. Waiting longer changes nothing; the record is in the wrong place. It is why DoDomain's connect flow reads the authoritative nameservers before it tells anyone where to click.

Resolution walks down the tree. The root servers say which servers handle .com; the .com registry servers hold NS records for every .com domain, naming its nameservers; those nameservers hold the domain's records. The NS records at the registry are the delegation, and the registrar is how you change them.

The zone also publishes NS records at its own apex. When the parent's list and the child's list disagree, resolvers may use either, and the domain works for some people and not for others. Nameservers that are listed but do not actually serve the zone, called lame delegations, cause the same intermittent failure.

Look up the domain's NS records. The nameserver names usually reveal the host: *.ns.cloudflare.com is Cloudflare, awsdns names are Route 53, domaincontrol.com is GoDaddy. A WHOIS or RDAP lookup names the registrar, which is a different question.

To check the delegation itself, ask the parent zone's servers rather than a resolver, for example dig NS example.com @a.gtld-servers.net for a .com domain, and compare it with what the domain's own nameservers return. Subdomains can be delegated too: if eu.example.com has its own NS records, records under it live at a different host from the rest of the domain.

The DNS provider detector does this walk for you: it finds the zone that owns a name, reads its authoritative nameservers, names the host, and says whether one-click setup is available there.

Moving DNS to another host changes only the delegation; the registration stays where it is. Copy every record to the new host first, then change the nameservers at the registrar, and keep the old zone correct until the long delegation TTL has expired. See DNS propagation for why that last step matters.

• DNS provider detector

  Name the host that actually serves a domain's zone, from its authoritative nameservers.

• DNS provider guides (docs)

  Where to add records at each of the DNS hosts DoDomain detects.

• DNS propagation

  Why a nameserver change is the slowest DNS change there is.