Knowledgebase

Help articles and plain-English explainers for the checks this tool runs.

• Delegation and nameservers ↗

  • Nameserver and MX hostname hygiene
  • Nameserver reachability: responding, TCP and public addresses
  • Open recursion and lame nameservers
  • Nameserver diversity and redundancy
  • Glue records: when your nameservers need them
  • Delegation: the parent must match your zone
• Mail ↗

  • Reverse DNS (PTR) for your mail servers
  • MX targets must not be CNAMEs
  • MX records: how your mail is routed
  • DMARC: from monitoring to enforcement
  • SPF: authorizing who can send your mail
• SOA and zone data ↗

  • SOA timers: refresh, retry, expire and minimum
  • SOA serial numbers and keeping servers in sync
• DNSSEC ↗

  • DNSSEC: the chain of trust
• Glossary ↗

  • How to read your report
  • How DNS resolution works: root, TLD, authoritative
  • TTL and caching
  • What is glue?
  • What is a delegation?
  • Authoritative vs recursive DNS
• Web and certificates ↗

  • Your website address: A, AAAA and www
  • CAA records: who may issue your certificates