DNS interrogation is a core passive and semi-active reconnaissance technique described in CEH v13 Reconnaissance Techniques. It allows ethical hackers to gather publicly available information about a target’s domain infrastructure.
Through DNS queries, testers can retrieve:
Subdomains (via zone transfers, brute force, or DNS records)
Mail server IP addresses (via MX records)
Server IP addresses, which can then be mapped to approximate geographic locations
However, DNS does not store authentication credentials such as usernames and passwords. That information resides in authentication systems like Active Directory, LDAP, or application databases, not DNS.
Therefore, Option A is the only choice that cannot be obtained via DNS interrogation. CEH v13 clearly distinguishes between naming infrastructure data and credential-based information, reinforcing why DNS enumeration cannot reveal user credentials.
Thus, Option A is correct.
