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Cisco 642-885 Exam Actual Questions

The questions for 642-885 were last updated at Oct. 9, 2021.
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  • Viewing questions 1-4 out of 136 questions

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Question #1 Topic 1

Referring to the topology diagram show in the exhibit,


which three statements are correct regarding the BGP routing updates? (Choose three.)

  • A. The EBGP routing updates received by R1 from R5 will be propagated to the R2, R4, and R7 routers
  • B. The EBGP routing updates received by R3 from R6 will be propagated to the R2 and R4 routers
  • C. The EBGP routing updates received by R1 from R5 will be propagated to the R2 and R4 routers
  • D. The IBGP routing updates received by R3 from R2 will be propagated to the R6 router
  • E. The IBGP routing updates received by R2 from R1 will be propagated to the R3 router
  • F. The IBGP routing updates received by R1 from R4 will be propagated to the R5, R7, and R2 routers
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Correct Answer: ABD

Question #2 Topic 1

When a BGP route reflector receives an IBGP update from a non-client IBGP peer, the route reflector will then forward the IBGP updates to which other router(s)?

  • A. To the other clients only
  • B. To the EBGP peers only
  • C. To the EBGP peers and other clients only
  • D. To the EBGP peers and other clients and non-clients
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Correct Answer: C

Question #3 Topic 1

Which two BGP mechanisms are used to prevent routing loops when using a design with redundant route reflectors? (Choose two.)

  • A. Cluster-list
  • B. AS-Path
  • C. Originator ID
  • D. Community
  • E. Origin
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Correct Answer: AC
http://www.cisco.com/en/US/docs/ios_xr_sw/iosxr_r3.7/routing/configuration/guide/rc37bgp.html
As the iBGP learned routes are reflected, routing information may loop. The route reflector model has the following mechanisms to avoid routing loops:
Originator ID is an optional, nontransitive BGP attribute. It is a 4-byte attributed created by a route reflector.
The attribute carries the router ID of the originator of the route in the local autonomous system. Therefore, if a misconfiguration causes routing information to come back to the originator, the information is ignored.
Cluster-list is an optional, nontransitive BGP attribute. It is a sequence of cluster IDs that the route has passed. When a route reflector reflects a route from its clients to nonclient peers, and vice versa, it appends the local cluster ID to the cluster-list. If the cluster-list is empty, a new cluster-list is created. Using this attribute, a route reflector can identify if routing information is looped back to the same cluster due to misconfiguration. If the local cluster ID is found in the cluster- list, the advertisement is ignored.

Question #4 Topic 1

Which two statements correctly describe the BGP ttl-security feature? (Choose two.)

  • A. This feature protects the BGP processes from CPU utilization-based attacks from EBGP neighbors which can be multiple hops away
  • B. This feature prevents IBGP sessions with non-directly connected IBGP neighbors
  • C. This feature will cause the EBGP updates from the router to be sent using a TTL of 1
  • D. This feature needs to be configured on each participating BGP router
  • E. This feature is used together with the ebgp-multihop command
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Correct Answer: AD
http://packetlife.net/blog/2009/nov/23/understanding-bgp-ttl-security/


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