Jack has not logged in to his e-mail account for a couple of weeks. Now, after entering his name and password, he receives an error message indicating that the username or password is invalid. What can he infer from this error message?
A)The physical layer is working.
B)Username and password are correct.
C)The network is suffering from traffic congestion.
D)The central router is down.

Question

Quizplus · Accepted Answer

The fact that the user is getting an invalid message proves that the physical layer is working properly.
Key Takeaway: Password Authentication Protocol (PAP) is a simple authentication protocol used to authenticate a user to a network access server used by Internet service providers. Authentication is a process of validating a user before allowing them access to server resources. If the server is sending a message stating that the username and password is invalid, it proves that the physical layer as well as layers 2, 3, and 4 are working since the authentication is taking place.

Jack Has Not Logged in to His E-Mail Account for a Couple