Chapter 12 - Wireless Networking

Question 1

You need to install wireless Internet access in an open warehouse environment. After installing the equipment, the technician notices varying signal strengths throughout the warehouse. How do you make sure there is full coverage?

Answer 1

1. C. It is imperative that a good site survey is completed before you install your wireless network. Trying various types of antennas and their placements is the key to covering the whole wireless area.

Question 2

Which of the following uses a certificate on both the server and client to provide the best wireless security with 802.1X (but is hardest to implement)?

Answer 2

2. C. TLS provides really good wireless security, but it’s hard to implement because you need to install a certificate on your server and also on all your clients. TTLS only uses a server-side certificate.

Question 3

What is the frequency range of the IEEE 802.11g standard?

Answer 3

3. C. The IEEE 802.11b and IEEE 802.11g both run in the 2.4 GHz RF range.

Question 4

Which devices can interfere with the operation of a wireless network because they operate on similar frequencies? (Choose two.)

Answer 4

4. B, D. If you are running 802.11b/g frequency, which most networks are, then you can receive interference from microwave ovens and cordless phones.

Question 5

Which wireless standard allows you to channel-bond to increase bandwidth and uses both the 2.4 GHz and 5 GHz frequencies?

Answer 5

5. D. 802.11n uses channel bonding of both the 2.4 GHz range and the 5 GHz range to get increased bandwidth of over 100 Mbps.

Question 6

Which of the following is considered a PAN?

Answer 6

6. D. Bluetooth works wirelessly to connect our phones, keyboards, and so on in small areas, also known as personal area networks (PANs).

Question 7

How many non-overlapping channels are available with 802.11a?

Answer 7

7. B. The IEEE 802.11a standard provides up to 12 non-overlapping channels, or up to 23 if you add the 802.11h standard.

Question 8

What is the maximum data rate for the 802.11a standard?

Answer 8

8. D. The IEEE 802.11a standard provides a maximum data rate of up to 54 Mbps.

Question 9

You need to install wireless on multiple floors of a large building and maintenance area. What is your first concern before installing the APs?

Answer 9

9. C. If you have a large area to cover with wireless, you need to be concerned with channel overlap.

Question 10

What is the maximum data rate for the 802.11b standard?

Answer 10

10. B. The IEEE 802.11b standard provides a maximum data rate of up to 11 Mbps.

Question 11

You connect a new host to your company’s wireless network. The host is set to receive a DHCP address and the WPA2 key is entered correctly. However, the host cannot connect to the network. What can the problem be?

Answer 11

11. B. If everything is correctly configured on the host, then MAC filtering would stop the host from connecting to the AP. If you try to connect and can’t, check the AP’s settings.

Question 12

Which is the highest encryption that WPA2 can use?

Answer 12

12. A. The IEEE 802.11i standard replaced Wired Equivalent Privacy (WEP) with a specific mode of the Advanced Encryption Standard (AES) known as the Counter Mode Cipher Block Chaining-Message Authentication Code (CBC-MAC) protocol. This allows AES-Counter Mode CBC-MAC Protocol (AES-CCMP) to provide both data confidentiality (encryption) and data integrity.

Question 13

Which additional configuration step is necessary in order to connect to an access point that has SSID broadcasting disabled?

Answer 13

13. C. If you disable SSID broadcasting, which you should, then you must configure the SSID name on the clients that need to connect to the AP.

Question 14

Which spread-spectrum technology does the 802.11b standard define for operation?

Answer 14

14. B. The IEEE 802.11b standard uses Direct Sequence Spread Spectrum (DSSS). If you are running 802.11g, it uses Orthogonal Frequency Division Multiplexing (OFDM).

Question 15

Which wireless LAN design ensures that a mobile wireless client will not lose connectivity when moving from one access point to another?

Answer 15

15. B. If you are running an extended service set (meaning more than one AP with the same SSID), you need to overlap the cell coverage by 10 percent or more so clients will not drop out while roaming.

Question 16

You have installed a point-to-point connection using wireless bridges and Omni directional antennas between two buildings. The throughput is low. What can you do to improve the link?

Answer 16

16. B. You need to use directional antennas, like a Yagi, to get the best signal between antennas.

Question 17

What does extended service set (ESS) ID mean?

Answer 17

17. A. Extended service set ID means that you have more than one access point, they all are set to the same SSID, and they are all connected together in the same VLAN or distribution system so users can roam.

Question 18

What is one reason that WPA encryption is preferred over WEP?

Answer 18

18. D. WPA is cool because it is easy to configure and works great. Type in a passphrase (assuming you’re using a pre-shared key) and you’re done. Plus, you have great security because the keys change dynamically.

Question 19

How wide are the channels used in 802.11n in order to gain the large bandwidth that the specification provides?

Answer 19

19. C. 802.11n uses two 20 MHz wide channels to create a 40 MHz wide channel, which provides over 100 Mbps wireless.

Question 20

802.11n uses MIMO. How does this optimize throughput to gain the high-speed advantage that 802.11n provides?

Answer 20

20. B. 802.11n MIMO sends multiple frames by several antennas over several paths. The frames are then recombined by another set of antennas to optimize throughput and multipath resistance. This is called spatial multiplexing.