Q1 (20 points) Choose the DNS server setting that will prevent an existing host and its IP...

Zone transfers allow DNS servers to replicate zone data (which includes all host records and their IP addresses). By controlling the access source of zone transfers, you restrict which servers can request and obtain this sensitive DNS data, preventing unauthorized disclosure of host information. Options A, C, and D address mail relay, CGI execution, and web directory listing respectively—none directly prevent DNS host and IP information disclosure.

Step-by-step Derivation:
DNS zone transfer (AXFR/IXFR) is the mechanism by which a secondary DNS server requests all records from a primary DNS server. This transfer includes all hostname-to-IP mappings in a zone. If zone transfers are unrestricted, an attacker can perform a zone transfer enumeration and discover all hosts and their IP addresses in a target domain. By implementing access controls on zone transfers (restricting them to only authorized secondary DNS servers), you prevent this reconnaissance attack. A) is about SMTP relay controls (email security). C) is about web server CGI security. D) is about web directory listing prevention. None of these protect DNS host enumeration.