NS lookup
See which name servers control a domain's DNS.
About NS lookup
What it is
The NS records (Name Server) specify which name servers are authoritative for a domain, that is, which servers answer all queries about the domain's DNS.
Why it matters
The name servers are the hub of the entire domain's DNS. If they sit with an unreliable or single provider, the domain becomes vulnerable to outages, and incorrect NS records can make the domain unreachable.
Tips
- Have at least two name servers, preferably with different providers, for redundancy.
- Check that the NS records match what the registrar has specified.
- Change name servers in an orderly way, changes take time to propagate.
Common questions
How many name servers should a domain have?
At least two, and ideally spread across different providers to withstand outages.
What happens if the name servers do not respond?
Then the domain's web and mail cannot be reached, because nothing can resolve its DNS.
More lookups
MX lookup
See which servers receive mail for a domain, and which provider handles it.
SPF check
Check whether a domain has an SPF record and how strictly it rejects spoofed mail.
DMARC check
See whether a domain has DMARC and which policy it uses against spoofed mail.
DKIM check
Look for DKIM signing on a domain using the most common selectors.
DNSSEC check
See whether a domain is protected with DNSSEC, that is, whether its DNS answers are signed.
TXT lookup
List all TXT records for a domain, including SPF, verifications and more.
Blacklist check
Check whether a domain's IP address is on blacklists such as Spamhaus, Barracuda and SpamCop.
A/AAAA lookup
See which IP addresses a domain points to, both IPv4 (A) and IPv6 (AAAA).
CNAME lookup
See whether a domain is an alias that points on to another domain.
SOA lookup
See the zone's core data: primary name server, contact and serial number.
CAA lookup
See which certificate authorities are allowed to issue certificates for the domain.
Reverse DNS (PTR)
Look up which host name a domain's IP address points back to.
MTA-STS
See whether a domain requires encrypted mail delivery via MTA-STS.
TLS-RPT
See whether a domain receives reports about failed encrypted mail delivery.
BIMI
See whether a domain publishes a logo that can be shown in the recipient's inbox.
SSL certificate
Check a domain's TLS certificate: issuer, validity and expiry.
Whois
See who owns a domain, when it was registered and when it expires.
HTTP security headers
Check whether a domain's website sets important security headers.