Authoritative name servers
DNS & Records
DNS Lookup Every DNS record for any domain A Record Lookup IPv4 addresses for a domain AAAA Record Lookup IPv6 addresses for a domain MX Lookup Mail servers for a domain NS Lookup Authoritative name servers TXT Lookup TXT records, SPF, verification CNAME Lookup Canonical name (alias) records SOA Lookup Start of Authority record SRV Lookup Service location records CAA Lookup Which CAs may issue certificates Reverse DNS (PTR) IP address to hostname DNSSEC Check Is the domain signed and validated? DNS Health Check A full delegation & DNS report cardEmail Deliverability
SPF Check Validate your Sender Policy Framework record DMARC Check Inspect and grade your DMARC policy DKIM Check Find and validate your DKIM public key Blacklist Check Check an IP against email blocklists (DNSBLs) SMTP Test Connect to a mail server and check STARTTLS MTA-STS Check Enforced TLS policy for inbound mail BIMI Check Brand logo record for email TLS-RPT Check SMTP TLS reporting policyNetwork & Web
SSL Certificate Check Inspect a site's TLS certificate and expiry HTTP Header Check Inspect response headers, redirects and security Ping (TCP) Reachability and latency over TCP Port Check Which common ports are openDomain
WHOIS Lookup Registration data for domains, IPs and ASNsNS (Name Server) records list the authoritative name servers for a domain — the servers that hold its DNS zone and answer queries about it. They are set at the registrar and delegate DNS resolution to your provider. Get them wrong and the entire domain can stop resolving, taking your website and email down with it.
DNS is a hierarchy. When a resolver looks up your domain, it asks the parent zone — the .com servers, say — which name servers are authoritative. The parent answers with your NS records, and the resolver then queries those servers directly for the actual records. This handoff is called delegation. The NS records exist in two places: at the registrar (the parent delegation) and inside your own zone. Both should agree, or you risk inconsistent and unreliable resolution.
IPeek returns the authoritative name servers published for the domain, typically two to four hostnames such as ns1.example-dns.com and ns2.example-dns.com. Confirm they match your DNS provider — Cloudflare, AWS Route 53, your registrar's own service, or a self-hosted setup. Most providers assign a fixed set, so a mismatch suggests an incomplete migration or a hijack. More than one name server is expected and healthy; it provides redundancy. If results look wrong, compare them against what your registrar shows.
The classic mistake is a delegation mismatch: the registrar points to one set of name servers while your zone lists another, causing intermittent failures as resolvers reach different servers. After moving DNS providers, update the NS records at the registrar and wait for the change to propagate before decommissioning the old zone. Having only one name server is fragile — add at least a second for redundancy. Lame delegation, where a listed server does not actually serve the zone, also breaks resolution and should be removed.
The registrar is where you register and manage the domain, while NS records name the servers that actually answer DNS queries for it. At the registrar you set which name servers are authoritative; those servers, run by your DNS provider, hold the zone with your A, MX and other records. The two roles can belong to different companies.
A domain should have at least two name servers for redundancy, and many providers assign three or four. Multiple name servers ensure that if one is unreachable, resolvers can still get answers from another. Relying on a single name server is a single point of failure that can take the whole domain offline.
This is a delegation mismatch, and it usually means a migration was left incomplete. The registrar's NS records control the actual delegation from the parent zone, so resolvers follow those. The NS records inside your zone should match them. Align both sets to avoid intermittent resolution failures.
NS changes at the registrar propagate through the parent zone and can take from a few hours up to 48 hours, depending on TTLs and registry processing. During this window, resolvers may use either the old or new name servers. Keep both sets serving identical records until propagation completes to avoid downtime.
Incorrect NS records can make the entire domain fail to resolve, taking down the website, email and every other service that depends on its DNS. Because NS records control delegation, an error here is more severe than a single bad record. Always verify changes with a fresh lookup before retiring old name servers.