Final answer:
Netcat is a versatile penetration testing tool, but an encrypted shell is not one of its functions.
Step-by-step explanation:
Netcat is a powerful penetration testing tool, often used for network exploration and security auditing. Although it has several functionalities, the one that is not a way to use netcat as the only tool is an encrypted shell. Netcat can be used for file transfer, port scanning, and creating reverse shells for remote access.