試験312-50v13-JPN トピック1 問題1050 スレッド

The described behavior matches DNS Zone Transfer Enumeration. In CEH reconnaissance, DNS enumeration aims to discover hosts and services by querying DNS records. A zone transfer is a special DNS operation intended for legitimate replication between an authoritative primary DNS server and its secondary DNS servers. When misconfigured, a DNS server may allow an unauthorized requester to perform a zone transfer, returning the entire DNS zone database. This can reveal extensive internal naming information such as subdomains, hostnames, mail exchangers, service records, and aliases, exactly like the "full list of internal mappings, including subdomains, mail hosts, and system aliases" described in the question. The clue
"secondary system responds unusually" is especially telling, because secondary DNS servers are commonly the ones configured for replication and may be mistakenly left open to transfers from any host.
The other options do not fit the output. LDAP enumeration targets directory services and would not yield DNS-style mappings unless you already had directory access and queries. NTP enumeration relates to time synchronization services and can reveal time/server details, not comprehensive host/subdomain lists.
NetBIOS enumeration focuses on Windows networking (names, shares, workgroups) typically on internal networks and would not produce a DNS zone's record set.
CEH-recommended mitigations include restricting zone transfers to authorized secondary server IPs only, using TSIG keys for authenticated transfers, minimizing publicly exposed DNS data, splitting internal and external DNS (split-horizon), and continuously auditing DNS configurations to prevent inadvertent information leakage.