Your client has a brand new laptop. He is trying to connect to his home network, which is using an older (802.11b) wireless router. The router is set for encryption but not MAC filtering. What is the most likely problem?

A.
His laptop has a newer operating system that cannot communicate with the router.

B.
His physical address for the laptop is not in the router.

C.
His laptop is using the WPA encryption protocol.

D.
The laptop does not have a wireless NIC.

Explanation:
Older routers use WEP; the newer laptop must be set to use the older WEP encryption protocol. Fact What is WEP? Hide Wired Equivalent Privacy (WEP) is a security protocol for wireless local area networks (WLANs). It has two components, authentication and encryption. It provides security, which is equivalent to wired networks, for wireless networks. WEP encrypts data on a wireless network by using a fixed secret key. WEP incorporates a checksum in each frame to
provide protection against the attacks that attempt to reveal the key stream.

Answer B is incorrect. Physical address is just another name for MAC address. Since MAC filtering is turned off, the physical address cannot be the problem.

Answer A is incorrect. The operating system is irrelevant.

Answer D is incorrect. All laptops made in the past several years come with wireless NICs.

Reference. http.//www.networkworld.com/details/715.html