CAS-001 · Question #452
The security engineer receives an incident ticket from the helpdesk stating that DNS lookup requests are no longer working from the office. The network team has ensured that Layer 2 and Layer 3…
The correct answer is D. NMAP. NMAP (Network Mapper) is the correct tool because it is specifically designed to scan ports and determine whether a service is listening on a given port. Running 'nmap -p 53 <DNS server IP>' will confirm whether port 53 (UDP/TCP) is open and a service is listening. The…
Question
The security engineer receives an incident ticket from the helpdesk stating that DNS lookup requests are no longer working from the office. The network team has ensured that Layer 2 and Layer 3 connectivity are working. Which of the following tools would a security engineer use to make sure the DNS server is listening on port 53?
Options
- APING
- BNESSUS
- CNSLOOKUP
- DNMAP
How the community answered
(29 responses)- A3% (1)
- B3% (1)
- D93% (27)
Explanation
NMAP (Network Mapper) is the correct tool because it is specifically designed to scan ports and determine whether a service is listening on a given port. Running 'nmap -p 53 <DNS server IP>' will confirm whether port 53 (UDP/TCP) is open and a service is listening. The distractors are wrong for these reasons: PING (A) tests basic ICMP reachability at Layer 3 but provides no information about whether a specific service/port is listening; NESSUS (B) is a vulnerability scanner - useful for finding vulnerabilities but overkill and not the direct tool for a simple port-listening check; NSLOOKUP (C) tests DNS name resolution functionality but does not verify the port state - if DNS is broken, NSLOOKUP would fail but would not tell you whether the issue is the port being closed vs. the DNS service being misconfigured.
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