Question 600
A company cannot explain why an old DNS mail exchanger still appears in public records. Which authorized assessment decision best addresses this particular situation?
Explanation
Correct Answer
Query authoritative DNS and compare MX records to the documented intended provider. This answer directly addresses the described constraint. Current DNS answers identify public mail routing independently of internal diagrams. Successful validation requires: The observed MX values match the latest authoritative zone response.
Incorrect Answers
That approach concerns a different situation: a client asks testers to discover public subdomains without sending packets to the client's servers. Certificate issuance logs expose hostnames passively but do not prove current ownership. The required result is that the observed MX values match the latest authoritative zone response. The appropriate action is: Query authoritative DNS and compare MX records to the documented intended provider.
That relates to a different issue: A tester needs to determine whether a reverse DNS entry identifies an assigned in-scope public address. Reverse names provide attribution hints but are not reliable proof of asset ownership. That is not a direct remedy for the requested outcome: The observed MX values match the latest authoritative zone response. The appropriate action is: Query authoritative DNS and compare MX records to the documented intended provider.
This action applies to a different case: An organization wants publicly exposed SSL certificate history for a retired hostname. Certificates can reveal previously registered names and issuance chronology. It does not establish the present requirement, where the observed MX values match the latest authoritative zone response. The appropriate action is: Query authoritative DNS and compare MX records to the documented intended provider.