Q1 /20 Choose the DNS server setting that will prevent an existing host and its IP address...
Accenture technical mcq question, verified with a worked answer. Free to practise - no sign-up.
/20
Choose the DNS server setting that will prevent an existing host and its IP address from being known.
Show answer & explanation
Zone transfers are the mechanism by which DNS data (including all host records and their IP addresses) is replicated from a primary DNS server to secondary servers. By controlling and restricting who can access zone transfers, you prevent unauthorized parties from discovering the complete DNS database containing all hosts and their IP addresses. Options A, C, and D relate to mail relay, CGI directories, and web server file listing respectively—none of which directly prevent DNS host-IP mappings from being known.
Step-by-step Derivation:
DNS Security Analysis:
Zone Transfer (Option B): A zone transfer (AXFR query) allows a secondary DNS server to request and download the entire DNS zone database from the primary server. This includes all host records (A records) and their corresponding IP addresses. Restricting zone transfers to authorized servers only prevents unauthorized reconnaissance of your network infrastructure.
Why other options are incorrect:
- Option A: Mail relay control prevents SMTP abuse but does not hide DNS records or host-IP mappings.
- Option C: CGI directory restrictions are web server security measures, unrelated to DNS disclosure.
- Option D: Directory file listing prohibition is also a web server setting, not a DNS security control.
Conclusion: Controlling zone transfer access is the primary DNS security mechanism for hiding the complete host-IP mapping database from external parties.