Subnet calculator

Query A, AAAA, MX, TXT, NS, SOA, CAA and more through public resolvers, with TTLs.

Check a domain's MX, SPF, DMARC, DKIM, MTA-STS and BIMI setup, with a pass/fail verdict per record.

Inspect a server's TLS certificate: issuer, SANs, expiry, key, protocol and cipher.

Follow a URL's redirect chain and inspect status codes, response headers and security headers.