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?

A.
PING

B.
NESSUS

C.
NSLOOKUP

D.
NMAP