Which of the following is the BEST way to prevent new users from connecting to a wireless access
point, but still allow already connected users to continue to connect?

A.
Create a MAC filter containing the current users.

B.
Turn off SSID broadcast.

C.
Change the encryption type to AES 256-bit for current users.

D.
Reduce the signal strength to 0 percent.

Explanation:

MAC Filtering (or EUI filtering, or layer 2 address filtering) refers to a security access control
method whereby the 48-bit address assigned to each network card is used to determine access to
the network.
MAC addresses are uniquely assigned to each card, so using MAC filtering on a network permits
and denies network access to specific devices through the use of blacklists and whitelists. While
the restriction of network access through the use of lists is straightforward, an individual person is
not identified by a MAC address, rather a device only, so an authorized person will need to have a
whitelist entry for each device that he or she would use to access the network.