[ Free tool · DNS & Mail Servers ]

NameServer Checker

List a domain's nameservers and catch lame or single-point-of-failure DNS.

[ About this tool ]

This NameServer checker lists a domain's authoritative NS records, resolves every nameserver to its IPv4 and IPv6 addresses, reads the SOA and flags lame delegation or missing redundancy.

How to read the results

  • ›You need at least two nameservers, ideally on different networks.
  • ›A nameserver with no address is a lame delegation and causes lookup failures.
  • ›Using a second DNS provider protects SPF, DKIM and DMARC lookups during outages.

Frequently asked questions

Why do nameservers matter for email authentication?

Receivers look up your SPF, DKIM and DMARC records through your nameservers. If they fail, those checks return temperror and mail can be deferred or rejected.

How many nameservers should a domain have?

At least two, as required by RFC 1034. Most providers give four, spread across separate networks.

Learn more in our guide: Email Security: Stop Spoofing, Phishing and BEC

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