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