A single 802.11 g access point has been configured and installed in the center of a square office. A few wireless users are experiencing slow performance and drops while most users are operating at peak efficiency. What are three likely causes of this problem? (Choose three.)

A.
mismatched TKIP encryption

B.
null SSID

C.
cordless phones

D.
mismatched SSID

E.
metal file cabinets

F.
antenna type or direction

Explanation:
A. Cordless phones may interfere in wireless NIC.
B. mismatched SSID
SSID(Service Set ldentifier)can also be written as ESSID, which is used to distinguish different networks and has 32 characters at most, WLAN cards set up different SSID to enter different networks. SSID is usually broadcast by AP, you can view SSID of the present area through XP built-in scanning feature .Taking security into consideration, SSID can be not broadcast, meanwhile users need to set up SSID manually to enter the appropriate network. In simple terms, SSID is the name of a local area network; only those computers that set up the same SSID values can communicate with each other. If SSID fails to match, wireless will fail in connection, and no wireless network inefficiency will appear.
C. metal file cabinets may have a certain amount of shielding
D. antenna type or direction