What port based network access control includes EAP, the roles of supplicant, authentication server, and authenticator; and was designed to provide authentication at layer 2 (before a node receives an IP address) in order to address the roaming infected laptop issue and multiple other issues) by requiring authentication before joining the network?

PPP

CHAP

802.1X

IPsec

SLIP

Explanation

802.1X is the correct answer as it is port based and authenticates at Layer 2. SLIP is a layer 2 protocol, but it isn't port based and it provides IP connectivity over asynchronous connections such as modems and serial lines. PPP replaced SLIP and supports synchronous connections as well as asynchronous connections; it is based on HDLC and added CIA, but is still not port based. CHAP is a secure authentication protocol that utilizes a 3 way handshake. IPsec is a suite of protocols that has been designed to provide CIA with the use of encryption for IPv6, but has also been ported for use in IPv4 where it addresses the lack of built in confidentiality over IPv4 at Layer 3 of the OSI model.

To use 802.1x, the client runs a piece of software known as the supplicant. The supplicant communicates with the authentication server. After successful authentication, the network switch or wireless access point allows the client to access the network.

This is a terribly worded question.