350-501 practice questions 51–60

1. Question 51 · 377 in bank

   

   Refer to the exhibit. Router 1 and router 2 are running OSPF Area 0. The router logs on both routers show that the LDP link has flapped. Which configuration must the engineer apply to the two routers to implement session protection on the link?

   • ARouter 1(config)# ip cef distributed Router 1(config)# mpls ldp session protection global Router 2(config)# ip cef distributed Router 2(config)# mpls ldp session protection global
   • BRouter 1(config)# ip cef distributed Router 1(config)# interface gigabitethernet 0/0 Router 1(config-if)# ip address 192.168.1.1 255.255.255.0 Router 1(config)# mpls ldp session protection Router 2(config)# interface gigabitethernet 0/0 Router 2(config-if)# ip address 192.168.1.2 255.255.255.0 Router 2(config)# mpls ldp session protection
   • CRouter 1(config)# ip cef distributed Router 1(config)# interface gigabitethernet 0/0 Router 1(config-if)# ip address 192.168.1.1 255.255.255.255 Router 1(config-if)# exit Router 1(config)# mpls ldp session protection Router 2(config)# ip cef distributed Router 2(config)# interface gigabitethernet 0/0 Router 2(config-if)# ip address 192.168.1.2 255.255.255.255 Router 2(config-if)# exit Router 2(config)# mpls ldp session protection
   • DRouter 1(config)# ip cef distributed Router 1(config)# interface gigabitethernet 0/0 Router 1(config-if)# ip address 192.168.1.1 255.255.255.0 Router 1(config-if)# mpls label protocol ldp Router 1(config-if)# mpls ip Router 1(config-if)# exit Router 1(config)# mpls ldp session protection Router 2(config)# ip cef distributed Router 2(config)# interface gigabitethernet 0/0 Router 2(config-if)# ip address 192.168.1.2 255.255.255.0 Router 2(config-if)# mpls label protocol ldp Router 2(config-if)# mpls ip Router 2(config-if)# exit Router 2(config)# mpls ldp session protection

   Show answer

   Answer: D

   Explanation

   By process of elimination, I labbed the commands. A: global keyword is not part of the command, mpls ldp session protection B: mpls ldp session proteccion command can't be entered in the interface configuration C: easiest elimination, bad subnet masks D: Correct answer

   Source: Adapted from community discussion — EdgardoAC

   References

   • Cisco documentation
   • Cisco documentation

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2. Question 52 · 377 in bank

   

   Refer to the exhibit. A network operator working for a telecommunication company with an employee id: 1234:56:789 is implementing a Cisco Unified MPLS solution. What is the effect of this implementation?

   • ABGP is deployed between the PEs and ABRs with RFC 9107.
   • BEIGRP is deployed between the PEs and ABRs with RFC 9107.
   • COSPF is deployed between the PEs and ABRs with RFC 3107.
   • DIS-IS is deployed between the PEs and ABRs with RFC 3107.

   Show answer

   Answer: A

   Explanation

   A it's right To use seamless the routers (ABRs) that join the segments must be BGP inline route-reflectors and the RFC 9107 is defined to BGP RR https://datatracker.ietf.org/doc/rfc9107/ https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/118846-config-mpls-00.html#anc8

   Source: Adapted from community discussion — chst

   References

   • Cisco documentation
   • RFC Editor

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3. Question 53 · 377 in bank

   A network engineer is configuring a newly installed PE router at the regional gateway location. The new PE router must use MPLS core routing protocols with the existing P router, and LDP sessions between the two routers must be protected to provide faster MPLS convergence. Which configuration must the engineer perform on the network so that LDP sessions are established?

   • AEnable RSVP-TE FRR on the LDP interface to protect the LDP session between routers.
   • BEnable communication over TCP port 646 T-LDP hello messages.
   • CSet the LDP session protection timer on each router to the same value.
   • DEnable LDP session protection on either one of the routers, which allows them to autonegotiate.

   Show answer

   Answer: C

   Explanation

   From Chst's comment (via Cisco Link) "...Both neighbor devices must be configured for session protection or one device must be configured for session protection and the other device must be configured to respond to targeted hellos..." If you build a quick lab between 2 routers (R1 and R2). - when you perform: R1(config)# mpls ldp session protection R2(config)# mpls ldp discovery targeted-hellos accept Then you will see that the targeted hello session will come up. However, if R2 does not accept targeted-hellos than the session protection will not work. From Karen's Comment: if you were to set the timer on both routers, then you would enable session protection on both routers. This will bring up the session: R1(config)# mpls ldp session protection duration 30 R2(config)# mpls ldp session protection duration 30 Although Cisco says that you can enable session protection on 1 router, it also says that the neighbor would need to be configured to accept targeted hellos. In this question we have no way of knowing targeted-hellos are enabled on either router thus, we are left with C being the best option.

   Source: Adapted from community discussion — Martiian

   References

   • Cisco documentation

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4. Question 54 · 377 in bank

   

   Refer to the exhibit. If router RA is configured as shown, which IPv4 multicast address space does it use?

   • A224.0.0.0/8
   • B225.0.0.0/8
   • C232.0.0.0/8
   • D239.0.0.0/8

   Show answer

   Answer: C

   Explanation

   Reference: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/3se/multicast/configuration_guide/b_mc_3se_3850_cg/ b_mc_3se_3850_cg_chapter_01011.html

   Source: Adapted from community discussion — Jondal

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5. Question 55 · 377 in bank

   DRAG DROP - Drag and drop the functions from the left onto the correct Path Computation Element Protocol roles on the right. Select and Place:

   

   This is an interactive task on the real exam — a drag-and-drop, hotspot or ordering question. There is nothing to select here, so the answer is shown below for reference.

   Show the answer figure

   Answer: See figure below

   Explanation

   Answer is: 1-1; 2-2; 3-4; 4-3; 5-5. - Rerefing to rfc4657 section-5.1.4 https://tools.ietf.org/html/rfc4657#section-5.1.4 The PCE facilitates path computation requests from Path Computation Clients (PCCs) to Path Computation Elements (PCEs). Path Computation Client requests path computation (calculation in our case) to Path Computation Element. - Rerefing to rfc4657 section-5.3.3 https://tools.ietf.org/html/rfc4657#section-5.3.3 If an LSP fails owing to the failure of a link or node that it traverses, a new computation request may be made to a PCE in order to repair the LSP. Since the PCC cannot know that the PCE's TED has been updated to reflect the failure network information, it is useful to include this information in the new path computation request. As a conclusion, PCC requests path calculation and includes update request in path calculation request.

   Source: Adapted from community discussion — MRasul18

   References

   • RFC Editor

   

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6. Question 56 · 377 in bank

   

   Refer to the exhibit. You are configuring an administrative domain in the given multi-vendor environment with PIM-SM. Which feature can you implement so that devices can dynamically learn the RP?

   • ABSR
   • BBIDIR-PIM
   • CAuto-RP
   • DSSM

   Show answer

   Answer: A

   Explanation

   Answer A: BSR | BSR is a standard and included in PIMv2, unlike AutoRP which is a Cisco proprietary protocol. Although Auto-RP has been adopted by some vendors, it's still not an "industry standard"

   Source: Adapted from community discussion — blizzlondon

   References

   • juniper.net documentation

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7. Question 57 · 377 in bank

   DRAG DROP - Drag and drop the multicast concepts from the left onto the correct descriptions on the right. Select and Place:

   

   This is an interactive task on the real exam — a drag-and-drop, hotspot or ordering question. There is nothing to select here, so the answer is shown below for reference.

   Show the answer figure

   Answer: See figure below

   Explanation

   I suggest: “Technology that requires an RP” – “PIM-SM” “technology that uses the RP as the single common root” – “shared tree” Def. from cisco book: “Shared tree: A shared tree is a single tree that is shared between all sources for each multicast group. The shared tree has a single common root, called a Rendezvous Point (RP)”. Def. from Wikipedia: “PIM Sparse Mode (PIM-SM) explicitly builds unidirectional shared trees rooted at a rendezvous point (RP) per group”

   Source: Adapted from community discussion — blizzlondon

   

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8. Question 58 · 377 in bank

   

   Refer to the exhibit. Which command is used to complete this configuration for QoS class-based marking?

   • APE-A(config-pmap-c)#set dscp ef
   • BPE-A(config-pmap-c)#priority
   • CPE-A(config-pmap-c)#random-detect
   • DPE-A(config-pmap-c)#fair-queue

   Show answer

   Answer: A

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9. Question 59 · 377 in bank

   What causes multicast traffic to permanently stay on the shared tree and not switch to the source tree?

   • ASSM range is being used
   • BThe RP announcements are being filtered
   • CThe SPT threshold is set to infinity
   • DThe RP IP address is configured incorrectly

   Show answer

   Answer: C

   Explanation

   I think C is correct: ip pim spt-threshold {kbps| infinity}[group-list access-list] Specifying the infinity keyword causes the router never to move to the shortest-path tree; it remains on the shared tree. This keyword applies to a multicast environment of "many-to-many" communication. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti_optim/configuration/12-4t/imc-optim-12-4t-book/imc_pim_sparse.html

   Source: Adapted from community discussion — nolbi

   References

   • Cisco documentation
   • Cisco documentation
   • Cisco documentation

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10. Question 60 · 377 in bank

    Which additional feature does MPLS DiffServ tunneling support?

    • Amatching EXP and DSCP values
    • BPHB layer management
    • Cusing GRE tunnels to hide markings
    • Dinteraction between MPLS and IGP

    Show answer

    Answer: B

    Explanation

    Reference: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mp_te_diffserv/configuration/15-mt/mp-te-diffserv-15-mt-book/mp-diffserv-tun-mode.html

    Source: Adapted from community discussion — pobaro

    References

    • Cisco documentation
    • Cisco documentation

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350-501 practice, question 51. 377 questions available.