BAOI · ANALYSE-SECURITE
DNS & domain analysis
Understand DNS analysis results
A and AAAA records point to IP addresses; MX identifies mail routing; NS lists authoritative nameservers; TXT commonly contains SPF policies and verification tokens.
DNS troubleshooting
- Check the exact domain name and desired record type.
- Compare authoritative responses with those returned to the affected client.
- Inspect TTL, cached values, split-horizon DNS and DNSSEC where relevant.
FAQ
Why might DNS results differ? Caching and recent configuration changes can lead to differing answers.
Does correct DNS guarantee a working website? No. TLS, HTTP and application availability require separate checks.
Practical example: read a DNS result
Try a public domain
Enter example.com without an https:// prefix or a path, then run the analysis. Review A, AAAA, MX, NS and TXT sections and note the values and TTLs relevant to the incident. Example results can change; compare them with the records actually expected for your domain.
Separate missing records from faults
An empty section means no value of that type is displayed for the query. A domain does not always need a CNAME or an AAAA record. For email, compare MX and SPF with the authorized sending and receiving services. Results reflect the service’s resolver; a workstation using internal DNS can receive a different answer.
Validate a DNS change
- Record the exact queried name, time and expected values before changing the configuration.
- Compare the new answer with authoritative DNS and with the affected workstation’s resolver.
- After DNS checks, test the actual HTTPS site, email delivery or application.
Technical references: RFC 1034 — DNS