Nathalie would like to perform a reliable scan against a remote target. She is not concerned about being stealth at this point. Which of the following type of scans would be the most accurate and reliable?

A.
A FIN Scan

B.
A Half Scan

C.
A UDP Scan

D.
The TCP Connect Scan

Explanation:
The connect() system call provided by your operating system is used to open a connection to every interesting port on the machine. If the port is listening, connect() will succeed, otherwise the port isn’t reachable. One strong advantage to this technique is that you don’t need any special privileges. This is the fastest scanning method supported by nmap, and is available with the -t (TCP) option. The big downside is that this sort of scan is easily detectable and filterable.