642-885 Deploying Cisco Service Provider Advanced Network Routing

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Question 1





Which three statements are correct regarding the various multicast groups? (Choose
three.)

  • A. Currently there is no source sending traffic to the 224.1.1.1 multicast group
  • B. PE5 has a Null OILforthe (*,224.0.1.40) entry
  • C. PE5 has a Null OILforthe (*,224.1.1.1) entry
  • D. CE5 has joined the 224.0.1.40 multicast group
  • E. CE5 has a Null OILforthe (*,224.1.1.1) entry


Answer : C,D,E

Explanation: #show ip mroute

Question 2

Which two statements regarding Auto RP operations and implementations are correct?
(Choose two.)

  • A. Candidate RPs send RP announcements to the 224.0.1.39 multicast group, and the mapping agents send RP discovery messages to the 224.0.1.40 multicast group
  • B. Every PIM-SM router must be configured with the RP mapping agent IP address
  • C. Candidate RPs learn the IP address of the mapping agents via periodic RP discovery messages
  • D. Administrative scoping can be configured to limit the scope of the RP announcements
  • E. A Reverse Path Forwarding check is done on the RP discovery messages
  • F. RP discovery messages are flooded hop by hop throughout the network as multicast to the all PIM routers multicast group with a TTL of 1


Answer : A,D

Explanation: Auto-RP Automatic route processing (Auto-RP) is a feature that automates the distribution of group- to-RP mappings in a PIM network. This feature has these benefits: It is easy to use multiple RPs within a network to serve different group ranges. It allows load splitting among different RPs. It facilitates the arrangement of RPs according to the location of group participants. It avoids inconsistent, manual RP configurations that might cause connectivity problems. Multiple RPs can be used to serve different group ranges or to serve as hot backups for each other. To ensure that Auto-RP functions, configure routers as candidate RPs so that they can announce their interest in operating as an RP for certain group ranges. Additionally, a router must be designated as an RP-mapping agent that receives the RP- announcement messages from the candidate RPs, and arbitrates conflicts. The RPmapping agent sends the consistent group-to-RP mappings to all remaining routers. Thus, all routers automatically determine which RP to use for the groups they support auto- rp candidate-rp To configure a router as a Protocol Independent Multicast (PIM) rendezvous point (RP) candidate that sends messages to the well-known CISCO-RP-ANNOUNCE multicast group (224.0.1.39), use the auto-rp candidaterp command in PIM configuration mode. To return to the default behavior, use the no form of this command. auto-rp candidate-rp type interface-path-id scope ttl-value [ group-list access-listname ] [ interval seconds ] [bidir] no auto-rp candidate-rp type interface-path-id scope ttl-value [ group-list access-listname] [ interval seconds ] [bidir]

Question 3

Which two options are characteristics ofconfiguration templates used by Cisco IOS XRto
optimize BGP peering implementations? (Choose two.)

  • A. Session groups are used to inherit address family-specific configurations.
  • B. Cisco IOS XR provides by default a session group operating with all the supported address families.
  • C. Session groups are used to inherit address family-independent configurations.
  • D. Session groups can be included within a neighbor group.
  • E. Session groups can include neighbor groups.


Answer : C,D

Question 4





Which two statements regarding the BGP peerlngs are correct? (Choose two)

  • A. On PE5,the incoming prefixes received from the 192.168.105.51 EBGP peer is limited to a maximum of 10 prefixes
  • B. On PE5, the "rplin" inbound route policy is applied to the 192.168.105.51 EBGP peer
  • C. On PE5, the "pass" outbound route policy is applied to the 192.168.105.51 EBGP peer
  • D. PE5 has one EBGP peer (CE5) and two IBGP peers (P1 and PE6)
  • E. PE5 has received a total of 60 prefixes from its neighbors


Answer : A,E

Explanation: #show ip bgp

Question 5

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


Answer : A,C

Explanation: 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 6

A network architect is responsible for the company's multicast network domain design.
Which multicast component acts as a meeting place for sources and receivers?

  • A. multicast shared tree
  • B. multicast distribution point
  • C. multicast rendezvous point
  • D. multicast source tree


Answer : C

Question 7

A network engineer for an ISP wants to reduce the number of iBGP adjacencies. A merge
is taking place with another ISP network, so the network engineer needs to make both
ASNs look like a single network for the Internet. Which BGP technology is most suitable?

  • A. route reflector
  • B. confederation
  • C. clustering
  • D. peer group


Answer : B

Question 8




Answer :

Question 9





Which three statements regarding the BGP operations are correct? (Choose three)

  • A. PE5 will set the local preferences 200 on all the prefixes sent to CE5
  • B. PE5 will set the local preference to 200 on all the prefixes learned from CE5
  • C. CE5 has received 5 prefixes from the PE5 EBGP peer
  • D. CE5 has the BGP scan interval set to 30 seconds
  • E. CE5 is announcing the 192.168.55.0/24 prefix via EBGP to the PE5 EBGP peer
  • F. The AS-Path to reach the 209.165.202.128/27 prefix from CE5 is: 64500 64497 64498


Answer : C,E,F

Explanation: #sh ip bgp | be Network #sh ip bgp #show ip bgp neighbors

Question 10

In secure multicast, which protocol is used to distribute secure keys to a multicast group?

  • A. ISAKMP
  • B. RSA
  • C. IPsec
  • D. GDOI
  • E. SKIP


Answer : D

Question 11

Refer to the exhibit.


Which option is the function of designing a hub and spoke confederation?

  • A. allows transit backbone area 66000 to be a blackhole for non-transit ASs
  • B. reduces the iBGP mesh, iBGP mesh will be in sub non-transit ASs
  • C. increases eBGP sessions between the confederation sub ASs
  • D. allows transit backbone area and non-transit ASs to run the same IGP


Answer : B

Question 12

Refer to the exhibit.


Which configuration ensures that RR2 does not send the same updates to PE2 that RR1
learns via PE1?

  • A. RR1 and RR2 should have different router IDs.
  • B. RR1 and RR2 should have different originator IDs.
  • C. RR1 and RR2 should have the same router IDs.
  • D. RR1 and RR2 should have the same cluster IDs.


Answer : D

Question 13

With IPv6 multicast, which feature can be used as a replacement method for static RP
configuration?

  • A. PIM Snooping
  • B. MLD
  • C. MLD Snooping
  • D. Embedded RP
  • E. DHCPv6


Answer : D

Question 14

On Cisco IOS-XR, which BGP configuration group allows you to define address-family
independent commands and address-family dependent commands for each address
family?

  • A. neighbor-group
  • B. session-group
  • C. af-group
  • D. peer-group


Answer : A

Explanation: Commands relating to a peer group found in Cisco IOS Release 12.2 have been removed from Cisco IOS XR software. Instead, the af-group, session-group, and neighbor-group configuration commands are added to support the neighbor in Cisco IOS XR software: The af-group command is used to group address family-specific neighbor commands within an IPv4 or IPv6 address family. Neighbors that have the same address family configuration are able to use the address family group name for their address family- specific configuration. A neighbor inherits the configuration from an address family group by way of the use command. If a neighbor is configured to use an address family group, the neighbor will (by default) inherit the entire configuration from the address family group. However, a neighbor will not inherit all ofthe configuration from the address family group if items are explicitly configured for the neighbor. The session-group command allows you to create a session group from which neighbors can inherit address family-independent configuration. A neighbor inherits the configuration from a session group by way of the use command. If a neighbor is configured to use a session group, the neighbor (by default) inherits the session group's entire configuration. A neighbor does not inherit all the configuration from a session group if a configuration is done directly on that neighbor. The neighbor-group command helps you apply the same configuration to one or more neighbors. Neighbor groups can include session groups and address family groups. This additional flexibility can create a complete configuration for a neighbor. Once a neighbor group is configured, each neighbor can inherit the configuration through the use command. If a neighbor is configured to use a neighbor group, the neighbor (by default) inherits the neighbor group's entire BGP configuration. However, a neighbor will not inherit all of the configuration from the neighbor group if items are explicitl

Question 15

Refer to the Cisco IOS DHCPv6 configuration shown in the exhibit.


Which statement is correct?

  • A. The configuration is missing a command under interface Gi0/1 to indicate to the attached hosts to use stateful DHCPv6 to obtain their IPv6 addresses
  • B. The IPv6 router advertisements indicate to the attached hosts on the Gi0/1 interface to get other information besides their IPv6 address via stateless auto configuration
  • C. The IPv6 DHCPv6 server pool configuration is misconfigured
  • D. The DNS server address can also be imported from another upstream DHCPv6 server


Answer : A

Explanation: Server Configuration In Global Configuration Mode ipv6 unciast-routing ipv6 dhcp pool <pool name> address prefix <specify address prefix> lifetime <infinite> <infinite> dns-server <specify the dns server address> domain-name <specify the domain name> exit In Interface Configuration Mode ipv6 address <specify IPv6 Address> ipv6 dhcp server <server name>rapid-commit Client Configuration In Global Configuration Mode enable configure terminal ipv6 unicast-routing In Interface Configuration Mode ipv6 address dhcp rapid commit ipv6 enable exit

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