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1.
Which one of the following is the common standard that defines wireless LAN
operation?
- A.IEEE 802.1
- B.IEEE 802.1x
- C.IEEE 802.11
- D.IEEE 802.3
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| The IEEE 802.11 standard focuses on wireless LAN definitions, methods, and operation. It is made up of many pieces, as described in Chapter 2, "RF Standards." Sometimes you might see IEEE 802.11x, which refers to the many subparts of 802.11. Be aware of the subtle difference between that and 802.1x, which defines port-based network access control. |
2.
Which of the following represent the frequency bands commonly used for wireless
LANs? (Choose two.)
- A.2.4 MHz
- B.2.4 GHz
- C.5.5 MHz
- D.11 GHz
- E.5 GHz
- Answer & Explanation
- Report
Answer : [B and E]
Explanation :
Explanation :
| Wireless LANs use the 2.4-GHz and 5-GHz bands. Be careful to notice the difference between megahertz (MHz) and gigahertz (GHz). Also remember that 5.5 Mbps and 11 Mbps are some of the common data rates used in wireless LANs, but those are not involved when you need to identify the frequency band. |
3.
Two transmitters are each operating with a transmit power level of 100 mW. When
you compare the two absolute power levels, what is the difference in dB?
- A.0 dB
- B.20 dB
- C.100 dB
- D.You can’t compare power levels in dB
- Answer & Explanation
- Report
Answer : [A]
Explanation :
Explanation :
| When the two power levels are the same, the result is 0 dB. As long as you remember the first handy Law of Zero, you will find exam questions like this easy. If not, you will need to remember that dB = 10log10 (100 mW / 100 mW) = 10log10 (1) = 0 dB. |
4.
A transmitter is configured to use a power level of 17 mW. One day it is reconfigured
to transmit at a new power level of 34 mW. How much has the power level increased
in dB?
- A.0 dB
- B.2 dB
- C.3 dB
- D.17 dB
- D.None of these answers are correct; you need a calculator to figure this out.
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| At first glance, 17 mW and 34 mW might seem like odd numbers to work with. Notice that if you double 17, you get 34. The second handy dB fact says that doubling a power level will increase the dB value by 3. |
5.
Transmitter A has a power level of 1 mW, and transmitter B is 100 mW. Compare
transmitter B to A using dB, and then identify the correct answer from the following
choices.
- A.0 dB
- B.1 dB
- C.10 dB
- D.20 dB
- E.100 dB
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
| Start with transmitter A’s level of 1 mW and try to figure out some simple operations that can be used to get to transmitter B’s level of 100 mW. Remember the handy Laws of 3s and 10s, which use multiplication by 2 and 10. In this case, 1 mW × 10 = 10 mW × 10 = 100 mW. Each multiplication by 10 adds 10 dB, so the end result is 10 + 10 = 20 dB. Notice that transmitter B is being compared to A (the reference level), which is 1 mW. You could also state the end result in dB-milliwatt (dBm). |
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