Free tools
DNS & email tools.
Check your DNS records, diagnose email authentication issues, and get actionable fixes — all free, no signup required.
Email authentication & deliverability
Diagnose SPF, DKIM, DMARC, and related records that determine whether your email lands in inboxes or spam.
DMARC Check
Find your DMARC record, understand the policy, and get a safer recommendation.
Live
SPF Check
Find your SPF record, count DNS lookups, and trace the include chain.
Live
DKIM Check
Look up DKIM selectors and verify your signing configuration.
Live
DMARC Record Generator
Build a safe DMARC record with explanations for every tag.
Guide
SPF Lookup Depth
Count DNS lookups in your SPF chain and see where you're spending them.
Guide
MX Check
Verify MX record priorities and detect common misconfigurations.
Guide
MTA-STS Check
Verify your MTA-STS policy for TLS enforcement on inbound email.
Guide
TLS-RPT Check
Check for SMTP TLS reporting records and reporting endpoints.
Guide
Recent Checks
See the most recent tool runs (local ops view).
Ops
Security & attack surface
Detect DNS misconfigurations that expose your domain to subdomain takeover, certificate abuse, and delegation drift.
Dangling DNS Check
Detect CNAMEs pointing to unclaimed SaaS targets (subdomain takeover risk).
Guide
Nameserver Check
Detect NS drift and registrar-vs-zone mismatches.
Guide
DNSSEC Check
Check DS records, DNSKEY presence, and chain-of-trust status.
Guide
CAA Record Check
Verify which certificate authorities can issue certs for your domain.
Guide
Guides
In-depth explanations of DNS and email security concepts, with practical advice.
Need more than free tools?
DNS Doctors offers continuous monitoring, white-glove managed DNS, and enterprise-grade audit reports.