300-420 practice questions 41–50

1. Question 41 · 359 in bank

   Select 2

   When designing interdomain multicast, which two protocols are deployed to achieve communication between multicast sources and receivers? (Choose two.)

   • AIGMPv2
   • BBIDIR-PIM
   • CMP-BGP
   • DMSDP
   • EMLD

   Show answer

   Answer: CD

   References

   • Cisco documentation

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2. Question 42 · 359 in bank

   

   Refer to the exhibit. A customer needs to apply QoS to the network management traffic passing through the GigabitEthernet 0/2 interface. All eight queuing classes are in use, so the new requirement must be integrated into the existing policy. Which solution must the customer choose?

   • AMark the traffic to DSCP CS6 and assign it to the ROUTING class. Then, prioritize traffic within the class.
   • BMark the traffic to DSCP CS2 and assign it to the ROUTING class. Then, baseline existing queue sizes to determine if additional bandwidth can be provisioned to the ROUTING class.
   • CMark the traffic to DSCP CS4 and assign it to the SIGNALLING class. Then, prioritize traffic within the class.
   • DMark the traffic to DSCP CS5 and assign it to the SIGNALLING class. Then, baseline existing queue sizes to determine if additional bandwidth can be provisioned to the SIGNALLING class.

   Show answer

   Answer: B

   Explanation

   Twelve-Class Egress Queuing Model Network control traffic (marked CS6), signaling traffic (marked CS3) and network management traffic (marked CS2) is all assigned to a dedicated nonpriority queue with a 10 percent bandwidth allocation; optionally, CS7 traffic may also be mapped to this queue. https://www.ciscopress.com/articles/article.asp?p=2159353&seqNum=3

   Source: Adapted from community discussion — CKL_SG

   References

   • Cisco documentation

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3. Question 43 · 359 in bank

   Select 2

   An architect must address sustained congestion on the access and distribution uplinks of a network. QoS has already been implemented and optimized, but it is no longer effective in ensuring optimal network performance. Which two solutions should the architect use to improve network performance. (Choose two.)

   • AConfigure selective packet discard to drop noncritical network traffic.
   • BBundle additional uplinks into logical EtherChannels.
   • CUtilize random early detection to manage queues.
   • DImplement higher-speed uplink interfaces.
   • EReconfigure QoS based on the IntServ model.

   Show answer

   Answer: BD

   Explanation

   As the question mentioned that QoS has been implemented and optimized, I can assumed A and C had been done. So I prefer B & D to upgrade the link and add new uplinks

   Source: Adapted from community discussion — andrewChan

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4. Question 44 · 359 in bank

   An engineer must design a QoS solution for a customer that is connected to an ISP over a 1Gbps link with a 100Mbps CIR. The ISP aggressively drops all traffic received over the CIR, which is causing numerous TCP retransmissions. The customer is not using any RTP applications but wants to maximize bandwidth usage up to the CIR. Which QoS solution should the engineer choose?

   • Apolicing
   • Bqueuing
   • Ctraffic shaping
   • Dpolicer with markdown

   Show answer

   Answer: C

   Explanation

   Policing is used for inbound traffic. The question states "The ISP aggressively drops all traffic RECEIVED.." so the traffic being dropped is traffic sent from the customer to the ISP. The ISP is using policing to drop traffic, but if wanted to control the amount of traffic being sent OUT of your network, you would use traffic shaping.

   Source: Adapted from community discussion — iLikeHamburgers

   References

   • Cisco documentation

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5. Question 45 · 359 in bank

   The customer solution requires QoS to support streaming multimedia over a WAN. An architect chooses to use Per-Hop Behavior. Which solution should the engineer use to classify and mark traffic traveling between branch sites?

   • ACBWFQ with DSCP AF2
   • BLLQ with DSCP EF
   • CCBWFQ with DSCP AF3
   • DLLQ with DSCP AF4

   Show answer

   Answer: C

   Explanation

   LLQ with EF seems way too strict for STREAMING multimedia (where one can actually take advantage of buffering). Judging by the various Cisco QoS baseline docs (even though the ones below are quite old), streaming video should be somewhere at AF3x/CS4. So I would go with C. https://www.cisco.com/en/US/technologies/tk543/tk759/technologies_white_paper0900aecd80295a9b.pdf https://community.cisco.com/t5/collaboration-voice-and-video/cisco-qos-baseline-classification-and-marking-and-mapping/ta-p/3108355

   Source: Adapted from community discussion — bogd

   References

   • Cisco documentation
   • Cisco documentation
   • cisco.com documentation

   Next question

6. Question 46 · 359 in bank

   

   Refer to the exhibit. Which solution decreases the EIGRP convergence time?

   • AEnable subsecond timers
   • BIncrease the hold time value
   • CIncrease the dead timer value
   • DEnable stub routing on the spokes

   Show answer

   Answer: A

   Explanation

   I disagree with Benzzyy. I think response D is correct : Query storms are eliminated, which saves bandwidth and CPU and allows the network to converge more quickly. https://www.cisco.com/en/US/technologies/tk648/tk365/technologies_white_paper0900aecd8023df6f.html

   Source: Adapted from community discussion — aymeric

   References

   • Cisco documentation

   Next question

7. Question 47 · 359 in bank

   An engineer must design an in-band management solution for a customer with branch sites. The solution must allow remote management of the branch sites using management protocols over an MPLS WAN. Queueing is implemented at the remote sites using these classes: ✑ Class1 equals voice traffic ✑ Class2 equals mission-critical traffic ✑ Class3 equals default traffic How must the solution prioritize the management traffic over the WAN?

   • AMark the traffic with DSCP EF and map into Class1 with a minimum bandwidth assigned by reducing the bandwidth available to Class2.
   • BMark the traffic with DSCP CS1 and map into Class2 with a minimum bandwidth assigned by reducing the bandwidth available to Class3.
   • CMark the traffic with DSCP CS6 and map into Class1 with a minimum bandwidth assigned by reducing the bandwidth available to Class2.
   • DMark the traffic with DSCP CS2 and map into Class2 with a minimum bandwidth assigned by reducing the bandwidth available to Class3.

   Show answer

   Answer: D

   Explanation

   It's D. CS2 is for OAM ('management'). Also, you wouldn't want to reduce the bandwidth for Class2 since it is specifically labeled mission-critical.

   Source: Adapted from community discussion — morlu

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8. Question 48 · 359 in bank

   An engineer is designing a multicast network for a company specializing in VoD content. Receivers are across the Internet, and for performance reasons, the multicast framework must be close to the receivers within each AS. For high availability, if the sources in one AS are no longer available, the receivers of that AS must be able to receive the VoD content from the sources in another AS. Which feature must the design include?

   • ASSM
   • Banycast RP
   • Cbidirectional PIM
   • DMSDP

   Show answer

   Answer: B

   Explanation

   option D, is also used to propagate multicast sources across different domains. However, it is primarily used for source discovery, and it does not directly handle high availability as effectively as anycast RP in this context.

   Source: Adapted from community discussion — PicoOstrava

   References

   • Cisco documentation

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9. Question 49 · 359 in bank

   An organization plans to deploy multicast across two different autonomous systems. Their solution must allow RPs to: ✑ discover active sources outside their domain ✑ use the underlying routing information for connectivity with other RPs ✑ announce sources joining the group Which solution supports these requirements?

   • ASSM
   • BMSDP
   • CPIM-DM
   • DPIM-SM

   Show answer

   Answer: B

   Explanation

   Reference: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/16-10/configuration_guide/ip_mcast_rtng/ b_1610_ip_mcast_rtng_9500_cg/b_1610_ip_mcast_rtng_9500_cg_chapter_010001.pdf

   Source: Adapted from community discussion — Lungful

   References

   • Cisco documentation
   • Cisco documentation

   Next question

10. Question 50 · 359 in bank

    Which type of rendezvous point deployment is standards-based and supports dynamic RP discovery?

    • Abootstrap router
    • BAnycast-RP
    • CAuto-RP
    • Dstatic RP

    Show answer

    Answer: A

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300-420 practice, question 41. 359 questions available.