CWNP CWNA-109 Exam - Topic 6 Question 16 Discussion

Actual exam question for CWNP's CWNA-109 exam

Question #: 16
Topic #: 6

Three access points are used within a facility. One access point is on channel 11 and the other two are on channel 1. The two access points using channel 1 are on either side of the access point using channel 11 and sufficiently apart so that they do not interfere with each other when they transmit frames. Assuming no other APs are in the vicinity, is CCI still a possibility in this network and why?

AYes, because the client devices connected to one of the channel 1 APs will transmit frames that reach the other channel 1 AP as well as clients connected to the other channel 1 AP.

BNo, because the APs are far enough apart that no CCI will occur.

CNo, because CCI only occurs in the 5 GHz frequency band.

DYes, because channel 11 loops around and causes CCI with channel 1.

Show Suggested Answer

Suggested Answer: A

CCI is still a possibility in this network because the client devices connected to one of the channel 1 APs will transmit frames that reach the other channel 1 AP as well as clients connected to the other channel 1 AP. CCI stands for co-channel interference, which is a type of interference that occurs when two or more devices transmit on the same channel within range of each other. CCI reduces performance and capacity because it causes contention and collisions on the wireless medium, which leads to retransmissions and delays. CCI can be mitigated by increasing physical separation between devices using the same channel or by reducing transmit power levels to limit coverage area. In this scenario, three access points are used within a facility. One access point is on channel 11 and the other two are on channel 1. The two access points using channel 1 are on either side of the access point using channel 11 and sufficiently apart so that they do not interfere with each other when they transmit frames. However, this does not prevent CCI from occurring between their client devices that are connected on channel 1. For example, if a client device connected to one of the channel 1 APs sends a frame to another device on the wired network or on another wireless network (such as an Internet server or a VoIP phone), that frame will be heard by both channel 1 APs as well as any other client devices connected to either of them on channel 1. This will cause CCI because these devices will have to wait for the channel to be clear before they can transmit their own frames. The answer that CCI only occurs in the 5 GHz frequency band is incorrect; CCI can occur in any frequency band where devices use the same channel. The answer that channel 11 loops around and causes CCI with channel 1 is also incorrect; channel 11 does not loop around and it operates in a different frequency band than channel 1.Reference:CWNA-109 Study Guide, Chapter 5: Radio Frequency Signal and Antenna Concepts, page 147

by Ira at Sep 17, 2024, 06:20 AM

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Mona

3 months ago

Nope, CCI isn't a problem here, they're too far apart.

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Cristy

3 months ago

Channel 11 and 1 can interfere, it's a valid concern.

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Fredric

3 months ago

Surprised to see people think CCI is only a 5 GHz issue!

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Salome

4 months ago

I disagree, the APs are spaced out enough.

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Moira

4 months ago

Yes, CCI can still happen with those channel 1 APs.

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Ming

4 months ago

I thought CCI could happen even in the 2.4 GHz band, but I'm not clear on how channel spacing affects that.

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Paulina

4 months ago

I feel like channel overlap could still cause issues, especially with the two APs on channel 1. Could they interfere with each other?

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Aja

4 months ago

I think I saw a similar question where distance between APs mattered. If they're far enough, maybe CCI isn't a concern?

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William

5 months ago

I remember studying about co-channel interference, but I'm not sure if it applies here since the APs are spaced out.

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Elmira

5 months ago

I'm a bit confused by the wording about the "channel 11 AP looping around" in option D. That doesn't seem to make sense to me. I'm leaning towards A or B as the most likely answers.

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Viva

5 months ago

Okay, let me think this through. The key information is that the two channel 1 APs are far enough apart to not interfere with each other, but the channel 11 AP is between them. I think the answer is A, but I'll double-check my reasoning.

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Marget

5 months ago

This question seems straightforward, but I want to make sure I understand the details correctly before answering.

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Sena

5 months ago

Based on the information provided, I believe the correct answer is A. Even though the channel 1 APs are far enough apart, the client devices connected to them can still cause CCI by transmitting frames that reach the other channel 1 AP.

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Nieves

5 months ago

Hmm, I'm a bit unsure about this one. I know stakeholder understanding is important, but I'm not sure which of these options is the most important reason. I'll need to think it through carefully.

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Lynelle

1 year ago

Ah, I'm torn between A and B. But I'll go with A just to be safe. Can't be too careful with CCI these days.

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Paulina

1 year ago

Haha, D is clearly the correct answer. Channel 11 looping around and causing CCI with channel 1? Classic networking shenanigans!

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Viki

1 year ago

I'm going with B. If the APs are sufficiently apart, there shouldn't be any CCI issues, right?

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Katie

1 year ago

I'm going with B. If the APs are sufficiently apart, there shouldn't be any CCI issues, right?

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Karol

1 year ago

B) No, because the APs are far enough apart that no CCI will occur.

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Jerrod

1 year ago

A) Yes, because the client devices connected to one of the channel 1 APs will transmit frames that reach the other channel 1 AP as well as clients connected to the other channel 1 AP.

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Kenneth

1 year ago

Hmm, I think the answer is A. Even though the APs are far apart, the client devices can still cause CCI between the channel 1 APs.

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Percy

1 year ago

B) No, because the APs are far enough apart that no CCI will occur.

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Yolande

1 year ago

Hmm, I agree. The client devices can definitely cause interference between the channel 1 APs.

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Luz

1 year ago

A) Yes, because the client devices connected to one of the channel 1 APs will transmit frames that reach the other channel 1 AP as well as clients connected to the other channel 1 AP.

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Leonardo

1 year ago

Oh come on, C? CCI has nothing to do with the 5 GHz band. This exam is trying to trick us!

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Darrin

1 year ago

I'm going to have to go with A on this one. The client devices are the key here, not just the APs.

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Melvin

1 year ago

D can't be right, channel 11 doesn't 'loop around' and cause interference with channel 1. That's just silly.

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Cecil

1 year ago

C) No, because CCI only occurs in the 5 GHz frequency band.

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Elke

1 year ago

B) No, because the APs are far enough apart that no CCI will occur.

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Michal

1 year ago

A) Yes, because the client devices connected to one of the channel 1 APs will transmit frames that reach the other channel 1 AP as well as clients connected to the other channel 1 AP.

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Dianne

1 year ago

But the APs are far enough apart, so I think CCI might not occur.

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Elizabeth

1 year ago

I agree with Ressie. The client devices might cause interference between the channel 1 APs.

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Antione

1 year ago

Nah, I'm going with B. The APs are far enough apart, so there should be no CCI.

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Margret

1 year ago

Nah, I'm going with B. The APs are far enough apart, so there should be no CCI.

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Rolande

1 year ago

B) No, because the APs are far enough apart that no CCI will occur.

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Rosina

1 year ago

A) Yes, because the client devices connected to one of the channel 1 APs will transmit frames that reach the other channel 1 AP as well as clients connected to the other channel 1 AP.

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Ressie

1 year ago

I think CCI is still a possibility in this network.

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Whitley

1 year ago

Hmm, I think the answer is A. Even though the APs are far apart, the client devices connected to one channel 1 AP can still interfere with the other channel 1 AP.

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