If an 802.llg Internet connection has connectivity problems, what may be the cause?

If an 802.llg Internet connection has connectivity problems, what may be the cause?
A . A cordless phone
B . A cellular phone
C . Incandescent lights
D . Electromagnetic interference (EMI)

Answer: D

Explanation:

Over the last 10 years 802.11 technology has made remarkable strides — getting faster, stronger and more scalable. But one problem still haunts Wi-Fi: reliability.

Nothing is more frustrating for network managers than users complaining about flaky Wi-Fi performance, spotty coverage and dropped connections. Dealing with a Wi-Fi environment that you can’t see and that is constantly changing is the problem. And radio frequency interference is the culprit.