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Exam 300-430 topic 1 question 36 discussion

Actual exam question from Cisco's 300-430
Question #: 36
Topic #: 1
[All 300-430 Questions]

A network engineer observes a spike in controller CPU overhead and overall network utilization after multicast is enabled on a controller with 500 APs. Which feature corrects the issue?

  • A. controller IGMP snooping
  • B. multicast AP multicast mode
  • C. broadcast forwarding
  • D. unicast AP multicast mode
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Suggested Answer: B 🗳️

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Citizenx
Highly Voted 2 years ago
Selected Answer: B
With multicast -unicast, the wlc would have to make a copy for every packet before sending it to an AP. WIth lots of AP, that would give a nice spike in cpu. By enabling multicast-multcast, now the wlc sends only 1 copy to a unique choosen multicast address and all APs joining that multicast address receive the packet.
upvoted 6 times
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rrahim
Most Recent 2 months, 1 week ago
Selected Answer: B
Unicast mode (D) sends individual copies of multicast packets to each AP. This increases CPU load on the WLC, as it must handle 500 separate unicast transmissions instead of one efficient multicast stream. Unicast is only useful when the network does not support multicast. Key Takeaways: ✔ Multicast mode should be used if the network supports it, as it reduces CPU load and network overhead. ✔ Unicast mode should only be used if multicast is not supported on the network. ✔ Multicast AP Multicast Mode is the best choice in this scenario.
upvoted 1 times
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DiegoECUIO
5 months, 3 weeks ago
Selected Answer: B
Multicast mode - In this mode, the controller sends multicast packets to a CAPWAP multicast group. This method reduces overhead on the controller processor and shifts the work of packet replication to your network, which is much more efficient than the unicast method. When you use a different VLAN/Subnet for AP and WLC, Multicast routing is mandatory on the wired side to support forwarding the downlink CAPWAP Multicast packet from WLC to AP.
upvoted 1 times
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Vlad_Is_Love_ua
1 year ago
Selected Answer: B
https://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/81671-multicast-wlc-lap.html#anc4
upvoted 1 times
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JimDiGriz
1 year, 1 month ago
Selected Answer: D
D is a correct one unicast AP multicast mode To correct this issue, the engineer should enable the "Unicast AP Multicast Mode" feature. This feature allows multicast traffic to be converted to unicast traffic and forwarded only to the APs that have clients that are interested in the multicast stream, instead of flooding the multicast traffic to all APs. This helps to reduce network congestion and improve overall network performance. Enabling "Multicast AP Multicast Mode" on the other hand, will cause the multicast traffic to be sent to all APs, increasing the network utilization and causing the controller CPU overhead to spike. This mode is not recommended in large wireless networks with many APs.
upvoted 1 times
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Pawnstar
2 years, 6 months ago
I take it back, the WLC should be configured for multicast-multicast mode. Provided answer is correct.
upvoted 2 times
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kthekillerc
2 years, 7 months ago
Correct answer should be D
upvoted 1 times
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Pawnstar
2 years, 7 months ago
answer is D.
upvoted 1 times
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Fortinet
2 years, 8 months ago
answer should be A
upvoted 1 times
Cyrillka
2 years, 7 months ago
No B is correct In Multicast-Unicast mode, each multicast packet is converted into a unicast packet and flooded to all the APs registered on that controller. Hence it is more CPU intensive and adds overhead on the controller.
upvoted 3 times
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C (25%)
B (20%)
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