CWS CWS Network Performance & Optimization 2 — Questions and Answers
Question 1: What does the term 'airtime fairness' refer to in WLAN management?
- Equal transmit power for all APs
- Allocating equal airtime to each client rather than equal data rate, preventing slow clients from monopolizing the channel (Correct answer)
- Distributing IP addresses fairly among clients
- Balancing SSIDs across frequency bands
Correct answer: Allocating equal airtime to each client rather than equal data rate, preventing slow clients from monopolizing the channel
Airtime fairness allocates equal channel time to each client, preventing older or slower devices from degrading throughput for faster clients.
Question 2: Which metric best indicates whether a wireless channel is congested from competing networks?
- RSSI
- Channel utilization percentage (Correct answer)
- DHCP lease count
- ARP table size
Correct answer: Channel utilization percentage
Channel utilization percentage shows how much of the available airtime is being consumed, including by neighboring networks on the same channel.
Question 3: What is MU-MIMO and how does it improve WLAN performance?
- Multi-User Multiple Input Multiple Output — allows an AP to transmit to multiple clients simultaneously, increasing throughput (Correct answer)
- Multi-Utility Managed IP Management Optimization — a QoS standard
- Maximum Uplink Monitoring for Internet and Mobile Operations — a monitoring protocol
- Multi-Unit Management Interface Module — a centralized controller feature
Correct answer: Multi-User Multiple Input Multiple Output — allows an AP to transmit to multiple clients simultaneously, increasing throughput
MU-MIMO allows a single AP to communicate with multiple clients at the same time using spatial streams, significantly improving overall network throughput.
Question 4: A network shows high retry rates on 2.4 GHz. What is the most effective optimization step?
- Increase DHCP lease time
- Identify and mitigate interference sources, and consider migrating clients to 5 GHz (Correct answer)
- Upgrade the RADIUS server
- Enable SSID broadcast
Correct answer: Identify and mitigate interference sources, and consider migrating clients to 5 GHz
High retry rates signal poor signal quality or interference; resolving interference and moving clients to 5 GHz reduces retries and improves reliability.
Question 5: What is the purpose of the Transmit Power Control (TPC) feature in enterprise WLANs?
- To manually set a fixed transmit power for compliance
- To dynamically adjust AP transmit power to optimize coverage and reduce co-channel interference (Correct answer)
- To control UPS battery output for AP power
- To limit client upload speeds
Correct answer: To dynamically adjust AP transmit power to optimize coverage and reduce co-channel interference
TPC dynamically reduces AP transmit power when neighboring APs provide sufficient coverage, minimizing co-channel interference.
Question 6: What does the term 'throughput' measure in a wireless network?
- The theoretical maximum link speed as advertised by the standard
- The actual data transfer rate achieved over the wireless medium under real conditions (Correct answer)
- The number of connected clients
- The latency in milliseconds between client and AP
Correct answer: The actual data transfer rate achieved over the wireless medium under real conditions
Throughput is the real-world data transfer rate, which is always lower than the theoretical PHY rate due to overhead, retransmissions, and contention.
CWS CWS Network Performance & Optimization 2
What does the term 'airtime fairness' refer to in WLAN management?