A customer has recently implemented a new wireless infrastructure using WLC-5520s at a site directly next to a large commercial airport. Users report that they intermittently lose Wi-Fi connectivity, and troubleshooting reveals it is due to frequent channel changes. Which two actions fix this issue? (Choose two.)
A customer at a site next to a large commercial airport experiences frequent Wi-Fi connectivity interruptions due to frequent channel changes. This issue is typically caused by radar interference which triggers Dynamic Frequency Selection (DFS) and forces access points to change channels to avoid radar. Removing UNII-2 and Extended UNII-2 channels from the 5 GHz channel list will help as these channels are shared with radar systems. Additionally, disabling DFS channels will prevent the access points from frequently changing channels due to radar detection requirements. These actions will stabilize the Wi-Fi connection in this environment.
DFS is Dynamic Frequency Selection, which is a function of using 5 GHz Wi-Fi frequencies that are generally reserved for radar. Because the 2.4Ghz band is free of radar, the DFS rules only apply to the 5.250 – 5.725 Ghz band. UNII-2 (5.250-5.350 GHz and 5.470-5.725 GHz) shared with radar systems. Therefore, APs operating on UNII-2 channels are required to use Dynamic Frequency Selection (DFS) to avoid interfering with radar signals.
Really..really?
I haven't see DFS in the official cert guide
man you talking about DFS not being covered in OCG, but its not the problem xD problem is that they are asking about high level wireless, its not topic for ENCOR.
DFS channels are actually extended UNII-2 and 3. To me the answer is C and D. Disable DFS as that will stop taking the radios down to scan for a free channel and stop using UNI2.
C and D
This mean answers are A & C ?
apologies I accidently upvoted you response. I meant to say it could not be A because the question states that there is frequent channel change. We need to stop that by disabling DFS,
At this stage, i believe the software they use to generate the exam questions from question bank is somehow glitchy as it mixes up different tracks together. How on earth such high level of channel selection can be asked for ENCOR exam ? what is then left for wireless track if they assume this is ok ???
C and D are correct
From Source: If you want to use the UNI II band DFS channels, don't have your site near an airport! If you have newer.... https://blog.iptel.com.au/wifi-and-the-problem-with-radar#:~:text=If%20you%20want%20to%20use%20the%20UNI%20II%20band%20DFS%20channels%2C%20don%27t%20have%20your%20site%20near%20an%20airport!%20If%20you%20have%20newer
my understanding of this is for answer A is "DFS channels because they are immune to radar interference" , they aren't immune. believe the question mentioned channel keeps changing is due to DFS, so the provided answer is right https://www.cisco.com/c/en/us/support/docs/wireless-mobility/80211/213882-radar-detection-in-dynamic-frequency-sel.html