CWNA 802.11 Standards & Protocol Architecture 2 — Questions and Answers
Question 1: Which Wi-Fi generation corresponds to the 802.11ax standard?
- Wi-Fi 5
- Wi-Fi 6 (Correct answer)
- Wi-Fi 6E
- Wi-Fi 7
Correct answer: Wi-Fi 6
802.11ax is branded as Wi-Fi 6 (and Wi-Fi 6E when extended to the 6 GHz band), introducing OFDMA and BSS Coloring.
Question 2: What does the term 'BSS Coloring' introduced in 802.11ax help achieve?
- Color-code SSID branding on client devices
- Reduce co-channel interference by tagging frames from different BSSs (Correct answer)
- Assign channels by color to APs automatically
- Enable multicolor LED status on APs
Correct answer: Reduce co-channel interference by tagging frames from different BSSs
BSS Coloring tags frames with a color identifier so devices can distinguish transmissions from overlapping BSSs and reduce unnecessary deferrals.
Question 3: What is the function of the DCF (Distributed Coordination Function) in 802.11?
- Centralized control of channel access by the AP
- Distributed contention-based channel access used by all stations (Correct answer)
- Priority queuing for voice and video traffic
- Power-saving scheduling for client devices
Correct answer: Distributed contention-based channel access used by all stations
DCF is the fundamental contention-based channel access method in 802.11, using CSMA/CA for all stations to share the medium.
Question 4: Which 802.11 amendment first introduced Quality of Service (QoS) through the WMM (Wi-Fi Multimedia) specification?
- 802.11e (Correct answer)
- 802.11i
- 802.11r
- 802.11k
Correct answer: 802.11e
802.11e introduced the Enhanced Distributed Channel Access (EDCA) mechanism that became the basis for WMM QoS in Wi-Fi.
Question 5: What is the role of the DTIM (Delivery Traffic Indication Message) beacon field?
- Indicate the AP's channel and SSID
- Signal sleeping clients that buffered multicast/broadcast frames are ready (Correct answer)
- Request a channel switch announcement
- Report current channel utilization to clients
Correct answer: Signal sleeping clients that buffered multicast/broadcast frames are ready
DTIM beacons alert power-saving clients that multicast or broadcast frames are buffered at the AP and about to be sent.
Question 6: In 802.11ac (Wi-Fi 5), what is the maximum number of spatial streams supported?
- 2
- 4
- 8 (Correct answer)
- 16
Correct answer: 8
802.11ac supports up to 8 spatial streams with MU-MIMO, enabling significantly higher aggregate throughput compared to 802.11n's 4 streams.
CWNA 802.11 Standards & Protocol Architecture 2
Which Wi-Fi generation corresponds to the 802.11ax standard?