SOA lookup
See the zone's core data: primary name server, contact and serial number.
About SOA lookup
What it is
The SOA record (Start of Authority) contains fundamental information about a DNS zone: which name server is primary, the contact person's email address and a serial number that increases with every change.
Why it matters
The SOA record controls how secondary name servers synchronise the zone. A correct SOA is the foundation for the entire DNS delegation working and for changes to propagate quickly.
Tips
- The serial number must increase with every change, the date format (YYYYMMDDNN) is the most common.
- The refresh and retry values control how quickly secondary servers fetch updates.
- The contact address is written with a dot instead of @, e.g. admin.company.com.
Common questions
Do I have to edit the SOA manually?
Usually not. DNS providers update the SOA automatically. But if you run your own name servers it is important to keep an eye on it.
What is the SOA serial number for?
It is a version number for the zone. Secondary servers compare the serial number with the one they have cached and fetch updated data if the number is higher.
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.
NS lookup
See which name servers control a domain's DNS.
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.
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.