Question 8
What three roles are defined by 802.1X? (Choose three)
A. AAA Server
B. Authenticatee
C. Authenticator
D. Authentication Server
E. Supplicant
Answer: C D E
Question 10
Which modulation technique allows you to achieve a data rate of 54Mb/s in the 2.4GHz-band?
A. Complimentary Code Keying
B. Differential Binary Phase Shift Keying
C. Differential Quadrature Phase Shift Keying
D. Quadrature Amplitude Modulation
Answer: D
Explanation
Quadrature Amplitude Modulation (QAM) is a method of combining two amplitude-modulated (AM) signals into a single channel, thereby doubling the effective bandwidth. In a QAM signal, there are two carriers, each having the same frequency but differing in phase by 90 degrees (so they are called quadrature carriers). Mathematically, one of the signals can be represented by a sine wave, and the other by a cosine wave. The two modulated carriers are combined at the source for transmission. At the destination, the carriers are separated, the data is extracted from each, and then the data is combined into the original modulating information.
With QAM method, 802.11g standard delivers the same 54 Mb/s maximum data rate as 802.11a, but operates in the
same 2.4-GHz band as 802.11b.
How are omni antennas in a wireless network most commonly polarized?
A. circularly
B. horizontally
C. vertically
D. both horizontally and vertically
Answer: C
Explanation
Omni antennas send a signal of the same strength in all directions. Antennae in wireless networks are often vertically polarized, which makes the electric field vertical.
Note: A VERTICALLY POLARIZED antenna transmits an electromagnetic wave with the E field perpendicular to the Earth’s surface.