Domain Checks

Everything to check after you buy a domain, and while you run one: DNS, name servers, email, website and certificate. Free, no sign-up.

DKIM selector (optional)

Your DKIM selector. Find it in the s= tag of a DKIM-Signature header in a mail you sent.

You can paste a web address or an email address. The domain is taken from it.

Technical details: every check, with the records and how to fix each one

How it works

DNS, email and DNSSEC checks run in your browser. They ask Cloudflare (1.1.1.1) and Google (8.8.8.8) over DNS over HTTPS.
Some checks need a server: the authoritative name servers, the website, the live certificate, Certificate Transparency (crt.sh) and the MTA-STS policy file. Our server in Germany does these over IPv4 only. It sends the domain name and nothing else. Answers are kept for 2 minutes. The limit is 60 requests a minute.
There is no WHOIS lookup. Instead, the name servers are compared as the registry, Cloudflare, Google and each name server see them.
Hosting and network names come from our own GeoLite2 lookup on asra.io.