Answer:
honestly I think the other one is correct
Explanation:
I believe its when some one does engineering as a hobby.
Answer:
A. Loopback tool
Explanation:
Loopback tool or adapter is a small device used to test networks ports and help identify simple network connection issues, this is a great tool when mapping out a physical layout of a network and quickly identify active ports on a switch.
This tool works by taking the transmitted signal and redirecting it or looping it back into the receiving end of the same connection.
Port 21
The server-PI (Server Interpreter) is
the process that listens to port 21 on the FTP server. The Server Interpreter
has control over server-DTP (Server Data Transfer Process), the method used for
data transfer connection. The server-PI must be in a position to respond to
standard FTP commands like USER and PASS and several other commands.