CWS Wireless Technologies & Network Fundamentals 2 — Questions and Answers
Question 1: Which IEEE 802.11 amendment introduced OFDMA as a key feature to improve multi-user efficiency?
- 802.11n
- 802.11ac
- 802.11ax (Correct answer)
- 802.11ad
Correct answer: 802.11ax
802.11ax (Wi-Fi 6) introduced OFDMA, allowing simultaneous transmissions to multiple clients by dividing channels into resource units.
Question 2: What is the primary purpose of a Distributed Antenna System (DAS) in wireless networking?
- Increase data encryption strength
- Extend coverage in large or obstructed venues (Correct answer)
- Reduce channel interference between APs
- Increase the number of SSIDs available
Correct answer: Extend coverage in large or obstructed venues
A DAS distributes antenna nodes throughout a building or venue to provide consistent wireless coverage in areas where a single AP would struggle.
Question 3: In the context of 802.11 networks, what does the term 'BSS' stand for?
- Broadband Signal Strength
- Basic Service Set (Correct answer)
- Beacon Synchronization System
- Bandwidth Sharing Standard
Correct answer: Basic Service Set
BSS (Basic Service Set) is the fundamental building block of an 802.11 WLAN, consisting of an AP and its associated client stations.
Question 4: Which frequency band is exclusively used by 802.11ad (WiGig) for very short-range, high-throughput communications?
- 2.4 GHz
- 5 GHz
- 6 GHz
- 60 GHz (Correct answer)
Correct answer: 60 GHz
802.11ad operates in the 60 GHz band, enabling multi-gigabit speeds over very short distances with limited wall penetration.
Question 5: What is the role of the Distribution System (DS) in an infrastructure-mode WLAN?
- Assigns IP addresses to wireless clients
- Connects access points to each other and to wired networks (Correct answer)
- Encrypts traffic between client and AP
- Manages QoS prioritization for voice traffic
Correct answer: Connects access points to each other and to wired networks
The Distribution System interconnects APs and bridges wireless traffic to the wired LAN, enabling roaming and inter-AP communication.
Question 6: Which modulation scheme offers the highest data rate in the 802.11ax (Wi-Fi 6) standard?
- 64-QAM
- 256-QAM
- 1024-QAM (Correct answer)
- 4096-QAM
Correct answer: 1024-QAM
Wi-Fi 6 (802.11ax) uses 1024-QAM as its highest modulation, encoding 10 bits per symbol for maximum throughput.
Question 7: A wireless client fails to roam smoothly between APs despite being in range of both. Which feature, when enabled, most directly improves this behavior?
- Band steering
- 802.11r Fast BSS Transition (Correct answer)
- DTIM interval tuning
- WMM power save
Correct answer: 802.11r Fast BSS Transition
802.11r (Fast BSS Transition) pre-authenticates clients with neighboring APs, drastically reducing roaming latency.
CWS Wireless Technologies & Network Fundamentals 2
Which IEEE 802.11 amendment introduced OFDMA as a key feature to improve multi-user efficiency?