CWS Wireless Technologies & Network Fundamentals 3 — Questions and Answers
Question 1: What is the maximum transmit power allowed for 5 GHz UNII-3 band operation in the United States under FCC rules?
- 30 dBm (Correct answer)
- 36 dBm
- 23 dBm
- 20 dBm
Correct answer: 30 dBm
The FCC allows up to 30 dBm (1 watt) EIRP for client devices in the UNII-3 (5.725–5.850 GHz) band.
Question 2: Which wireless topology allows devices to communicate directly with each other without an access point?
- Infrastructure BSS
- Extended Service Set
- Independent BSS (IBSS) (Correct answer)
- Mesh BSS
Correct answer: Independent BSS (IBSS)
An IBSS (Independent Basic Service Set), also called ad hoc mode, lets devices communicate peer-to-peer without an AP.
Question 3: What does RSSI measure in a wireless network?
- The ratio of signal to noise at the receiver
- The relative received signal strength from an AP (Correct answer)
- The retransmission rate of a wireless client
- The encryption key strength of a WPA session
Correct answer: The relative received signal strength from an AP
RSSI (Received Signal Strength Indicator) is a relative measure of the power of the received radio signal, typically expressed in dBm.
Question 4: Which 802.11 feature allows an AP to dynamically switch channels to avoid radar interference in the 5 GHz band?
- TPC (Transmit Power Control)
- DFS (Dynamic Frequency Selection) (Correct answer)
- BSS Coloring
- MU-MIMO
Correct answer: DFS (Dynamic Frequency Selection)
DFS enables APs to detect radar systems and automatically move to a different channel to avoid interference, as required by FCC/ETSI regulations.
Question 5: A network uses 20 MHz channels in the 2.4 GHz band. How many non-overlapping channels are available in the US?
- 2
- 3 (Correct answer)
- 4
- 11
Correct answer: 3
In the US 2.4 GHz band, only channels 1, 6, and 11 are non-overlapping when using 20 MHz channel widths.
Question 6: What is the significance of the 'guard interval' in OFDM-based 802.11 transmissions?
- It separates SSIDs on the same AP
- It prevents inter-symbol interference caused by multipath (Correct answer)
- It defines the gap between adjacent channels
- It is the time between beacon frames
Correct answer: It prevents inter-symbol interference caused by multipath
The guard interval is a short pause between OFDM symbols that prevents inter-symbol interference caused by delayed multipath reflections.
Question 7: Which protocol is used by WPA3-Personal to replace the PSK handshake and provide forward secrecy?
- TKIP
- SAE (Simultaneous Authentication of Equals) (Correct answer)
- EAP-TLS
- CCMP-256
Correct answer: SAE (Simultaneous Authentication of Equals)
WPA3-Personal replaces the 4-way handshake PSK exchange with SAE (Dragonfly handshake), which provides perfect forward secrecy and resistance to offline dictionary attacks.
CWS Wireless Technologies & Network Fundamentals 3
What is the maximum transmit power allowed for 5 GHz UNII-3 band operation in the United States under FCC rules?