CWT Troubleshooting & Maintenance Procedures 4 — Questions and Answers
Question 1: A Wi-Fi 6 (802.11ax) AP is installed in a warehouse, but clients only connect at 802.11n rates. What is the most likely reason?
- Wi-Fi 6 is incompatible with warehouse environments
- The client devices do not support 802.11ax (Correct answer)
- The AP's MIMO streams are set to 1x1
- The AP is operating on the 6 GHz band exclusively
Correct answer: The client devices do not support 802.11ax
Clients can only negotiate the highest rate mutually supported; if client NICs are 802.11n-only, they will connect at 802.11n rates regardless of AP capability.
Question 2: You observe that clients near AP boundaries are 'sticky' and do not roam to a closer AP. What feature can help resolve this?
- Band steering
- 802.11r fast BSS transition or BSS transition management (802.11v) (Correct answer)
- Dynamic Frequency Selection (DFS)
- MU-MIMO
Correct answer: 802.11r fast BSS transition or BSS transition management (802.11v)
BSS Transition Management (802.11v) allows the AP to suggest better APs to clients, encouraging roaming away from a distant AP.
Question 3: During preventive maintenance, a technician inspects AP mounting locations. Which condition requires immediate attention?
- The AP's LED is blinking green
- The AP enclosure shows signs of water ingress or corrosion (Correct answer)
- The AP is mounted on a ceiling tile
- The AP's cable management tie wraps are aging
Correct answer: The AP enclosure shows signs of water ingress or corrosion
Water ingress or corrosion can cause hardware failure, electrical hazards, and void warranties, requiring immediate remediation.
Question 4: What is the effect of setting the minimum basic rate too low (e.g., 1 Mbps) on a busy WLAN?
- Faster overall network throughput for all clients
- Legacy clients consume more airtime, reducing performance for all users (Correct answer)
- Reduced co-channel interference between APs
- Improved roaming behavior for 802.11r clients
Correct answer: Legacy clients consume more airtime, reducing performance for all users
Lower minimum basic rates allow legacy clients to stay connected at slow rates, consuming excessive airtime and degrading the entire cell's capacity.
Question 5: A technician uses a Wi-Fi analyzer and sees dozens of SSIDs on channel 6 in the 2.4 GHz band. The recommended action is:
- Configure all APs to also use channel 6 to match the environment
- Move the APs to non-overlapping channels 1 or 11 to reduce co-channel interference (Correct answer)
- Disable 2.4 GHz and use 5 GHz exclusively on all APs
- Increase transmit power on all 2.4 GHz APs to overpower neighbors
Correct answer: Move the APs to non-overlapping channels 1 or 11 to reduce co-channel interference
Moving to channels 1 or 11 reduces co-channel interference when channel 6 is saturated with neighboring networks.
Question 6: After a power outage, several APs do not come back online. The most likely cause is:
- The APs lost their radio firmware permanently
- The PoE switch or injectors did not restore power to all ports (Correct answer)
- The APs need manual channel reassignment after a reboot
- The WLC blacklisted the APs during the outage
Correct answer: The PoE switch or injectors did not restore power to all ports
PoE switches sometimes do not restore power to all ports after a power event due to budget limits or port priority settings.
Question 7: A client reports intermittent connectivity that correlates with microwave oven use in the break room. Which band and channel combination is most affected?
- 5 GHz, channel 36
- 2.4 GHz, channel 6 (Correct answer)
- 5 GHz, channel 149
- 2.4 GHz, channel 11
Correct answer: 2.4 GHz, channel 6
Microwave ovens emit RF energy around 2.45 GHz, which overlaps with the 2.4 GHz Wi-Fi band and particularly impacts channels near the center of the band such as channel 6.
CWT Troubleshooting & Maintenance Procedures 4
A Wi-Fi 6 (802.11ax) AP is installed in a warehouse, but clients only connect at 802.11n rates.
What is the most likely reason?