Practice Free CWNA-109 Exam Online Questions
You are attempting to explain RF shadow and how it can cause lack of coverage.
What common building item frequently causes RF shadow and must be accounted for in coverage plans?
- A . Wooden doors
- B . Carpeted floors
- C . Elevators
- D . Cubicle partitions
Which HT protection modes allow only for the association of HT stations in the HT basic service set? (Choose all that apply.)
- A . Mode 0―Greenfield mode
- B . Mode 1―HT nonmember protection mode
- C . Mode 2―HT 20 MHz protection mode
- D . Mode 3―HT Mixed mode
Which of the following are good uses for portable networks? (Choose all that apply.)
- A . Military maneuvers
- B . Disaster relief
- C . Construction sites
- D . Manufacturing plants
What factors will have the most significant impact on the amount of wireless bandwidth available to each station within a BSS? (Choose 2)
- A . The number of client stations associated to the BSS
- B . The power management settings in the access point’s beacons
- C . The presence of co-located (10m away) access points on non-overlapping channels
- D . The data rates at which nearby client stations are transmitting and receiving data
- E . The layer 3 protocol used by each station to transmit data over the wireless link
Which logical plane of network operation is typically defined by protocols and intelligence?
- A . User plane
- B . Data plane
- C . Network plane
- D . Control plane
- E . Management plane
What does 802.1X/EAP provide when implemented for WLAN security? (Choose all that apply.)
- A . Access to network resources
- B . Verification of access point credentials
- C . Dynamic authentication
- D . Dynamic encryption-key generation
- E . Verification of user credentials
Name potential sources of interference in the 5 GHz U-NII band. (Choose all that apply.)
- A . Perimeter sensors
- B . Nearby OFDM (802.11a) WLAN
- C . FM radio
- D . DSSS access point
- E . Bluetooth
- F . Nearby HT (802.11n) WLAN
A robust security network (RSN) requires the use of which security mechanisms? (Choose all that apply.)
- A . 802.11x
- B . WEP
- C . IPsec
- D . CCMP/AES
- E . CKIP
- F . 802.1X
What percentage of cell overlap is needed to provide for seamless roaming?
- A . 10 percent
- B . 15 percent
- C . 20 percent
- D . 25 percent
- E . This is a trick question.
In an 802.11 2.4 GHz system, what 22 MHz channels are considered non-overlapping?
- A . 7 and 11
- B . 2 and 8
- C . 1 and 5
- D . 4 and 6
C
Explanation:
In the 2.4 GHz frequency band used for 802.11 wireless networks, the channel bandwidth is typically 20 MHz, but the actual frequency spread of each channel is about 22 MHz due to the modulation techniques used. This spread causes overlap between adjacent channels, which can lead to interference and degrade network performance. To avoid this, it’s essential to use non-overlapping channels.
The three non-overlapping channels in the 2.4 GHz band are 1, 6, and 11. Each of these channels is spaced sufficiently apart to avoid interference with each other: Channel 1: Centered at 2.412 GHz.
Channel 6: Centered at 2.437 GHz.
Channel 11: Centered at 2.462 GHz.
Given the options provided, option C (1 and 5) is the closest to a pair of non-overlapping channels, although in practice, channel 5 would still cause some interference with channel 1 due to the 22 MHz spread. The ideal choice for non-overlapping channels would be any two channels among 1, 6, and 11, but this is not an option provided. Therefore, within the given options, 1 and 5 are the best choice, understanding that in a real-world scenario, 1 and 6 or 6 and 11 would be preferred to avoid overlap.
Reference: CWNA Certified Wireless Network Administrator Official Study Guide: Exam CWNA-109, by David D. Coleman and David A. Westcott.
Understanding 2.4 GHz channel arrangement and interference patterns in 802.11 wireless networks.