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QUESTION 81
Refer to the exhibit. Which three statements are correct regarding the Cisco IOS-XR configuration? (Choose three.)
A. This router, acting as the RP mapping agent, will send RP announcement messages to the 224.0.1.40 group
B. This router, acting as the RP mapping agent, will send RP discovery messages to the 224.0.1.39 group
C. This router is the RP mapping agent only for the 224.11.11.11 and 224.99.99.99 multicast groups
D. This router is a candidate PIM-SM RP for the 224.99.99.99 multicast group
E. This router is a candidate PIM-BIDIR RP for the 224.11.11.11 multicast group
F. IGMPv3 is enabled on all interfaces
G. Other routers will recognize this router as the RP for all multicast groups with this router loopback 0 IP address
Answer: DEF
QUESTION 82
Refer to the exhibit. XR4 must protect itself from a DOS attack against its BGP process from R1 by using the TTL security feature. Which configuration achieves this goal?
A. router bgp 100
neighbor 10.10.14.1 ttl-security
B. router bgp 100
neighbor 10.10.14.1 ttl-security hops 1
C. router bgp 100
neighbor 10.10.14.1 ttl-security hops 254
D. router bgp 100
neighbor 10.10.14.1 ttl-security hops 255
Answer: A
QUESTION 83
Each router (RTA, RTB, and RTC) has one iBGP adjacency with the route reflector router RTD. Router RTC has an iBGP route advertised by RTA, but the same route is missing from RTB. Thenetwork engineer verifies that route filtering does not deny the route advertisement. Which action corrects the problem?
A. RTD(config-router)#neighbor 192.168.1.1 route-reflector-client
RTD(config-router)#neighbor 192.168.1.1 description RTA
RTD(config-router)#neighbor 192.168.1.2 route-reflector-client
RTD(config-router)#neighbor 192.168.1.2 description RTB
B. RTC(config-router)#neighbor 192.168.1.4 route-reflector-client
RTC(config-router)#neighbor 192.168.1.4 description RTD
C. RTA(config-router)#neighbor 192.168.1.4 route-reflector-client
RTA(config-router)#neighbor 192.168.1.4 description RTD
RTB(config-router)#neighbor 192.168.1.4 route-reflector-client
RTB(config-router)#neighbor 192.168.1.4 description RTD
D. RTB(config-router)#neighbor 192.168.1.3 route-reflector-client
RTB(config-router)#neighbor 192.168.1.3 description RTC
E. RTB(config-router)#neighbor 192.168.1.3 route-reflector-client
RTB(config-router)#bgp cluster-id 192.168.1.2
RTB(config-router)#no bgp client-to-client reflection
Answer: A
QUESTION 84
Which informationdoes the multicast supported router need to forward the multicast traffic over the source or shared tree?
A. source address
B. multicast address
C. destination address
D. mGRE headers
E. MDT Data
Answer: C
QUESTION 85
Which IPv6 mechanism occurs between a provider edge router and the customer premises equipment router to allow an ISP to automate the process of assigning a block of IPv6 addresses to a customer for use within the customer network?
A. Router Advertisement
B. DHCPv6 Prefix Delegation
C. DHCPv6 Lite
D. Stateful DHCPv6
Answer: B
Explanation:
http://www.cisco.com/en/US/tech/tk872/technologies_configuration_example09186a0080b8a116.shtml
QUESTION 86
Which multicast routing protocol supports dense mode, sparse mode and bidirectional mode?
A. DVMRP
B. MOSPF
C. PIM
D. MP-BGP
E. MSDP
Answer: C
QUESTION 87
To which three IP multicast groups can a multicast MAC address “01-00-5E-4D-62-B1” listen? (Choose three.)
A. 231.205.98.177
B. 231.205.99.177
C. 239.77.98.177
D. 239.205.99.177
E. 224.205.98.177
F. 224.205.99.177
Answer: ACE
QUESTION 88
Refer to the exhibit. R5 is configured as the RP for the PIM-SM domain for AS 1020. If R3 and R4 are correctly configured, which Cisco IOS-XE configuration should be done on R5 to configure it as a PIMv3 BSR router?
A. ip pim send-rp-announce loopback 0 scope 16
int gi1/3 , gi 1/4
ip pim sparse-mode
int gi 1/1
ip pim bsr-border
B. ip pim rp-candidate loopback 0
int gi1/3 , gi 1/4
ip pim sparse-mode
int gi 1/1
ip pim bsr-border
C. ip pim rp-candidate loopback 0
int gi1/3 , gi 1/4
ip pim sparse-mode
ip pim bsr-border
D. ip pim send-rp-announce loopback 0 scope 16
int gi1/3 , gi 1/4
ip pim sparse-mode
ip pim bsr-border
Answer: B
QUESTION 89
Which two features are used to provide high availability multicast? (Choose two.)
A. BFD
B. NSF/SSO
C. PIM NSR
D. PIM triggered join
E. IGMP triggered report
F. MSDP
Answer: BD
Explanation:
Triggered joins are sent when the primary or the secondary RPF information changes.
No RPF change prunes are sent for MoFRR streams.
mofrr
To perform a fast convergence (multicast-only fast reroute, or MoFRR) of specified routes/flows when a failure is detected on one of multiple equal-cost paths between the router and the source, use the mofrr command under PIM configuration mode.
mofrr rib acl_name
no rib acl_name
QUESTION 90
Which two statements correctly describe the RPF check when a multicast packet arrives at a router? (Choose two.)
A. The router looks up the source address in the unicast routing table to determine if the packet has arrived on the interface that is on the reverse path back to the source
B. The router looks up the destination address in the unicast routing table to determine if the packet has arrived on the interface that is on the reverse path back to the destination
C. If the packet has arrived on the interface leading back to the destination, the RPF check passes and the packet is forwarded. If the RPF check fails, the packet is dropped
D. If the packet has arrived on the interface leading back to the source, the RPF check passes and the packet is forwarded. If the RPF check fails, the packet is dropped
Answer: AD
Explanation:
Reverse Path Forwarding (RPF)
RPF is a fundamental concept in multicast routing that enables routers to correctly forward multicast traffic down the distribution tree. RPF makes use of the existing unicast routing table to determine the upstream and downstream neighbors. A router will only forward a multicast packet if it is received on the upstream interface.
This RPF check helps to guarantee that the distribution tree will be loop free.
RPF Check
When a multicast packet arrives at a router, the router will perform an RPF check on the packet.
If the RPF check is successful, the packet will be forwarded. Otherwise it will be dropped.
For traffic flowing down a source tree, the RPF check procedure works as follows:
Step 1. Router looks up the source address in the unicast routing table to determine if it has arrived on the interface that is on the reverse path back to the source.
Step 2. If packet has arrived on the interface leading back to the source, the RPF check is successful and the packet will be forwarded.
Step 3. If the RPF check in 2 fails, the packet is dropped.
QUESTION 91
Refer to the EBGP configuration on a PE IOS-XR router exhibit.
After the EBGP configuration, no routes are accepted from the EBGP peer, nor are any routes advertised to the EBGP peer.
What could be the problem?
A. The update-source neighbor configuration command must also be configured
B. The next-hop-self neighbor configuration command must also be configured
C. EBGP neighbors must have an inbound and outbound route policy configured
D. An access list is blocking IP protocol 179 packets between the two EBGP peers
E. The maximum-prefix neighbor configuration command must also be configured
Answer: C
QUESTION 92
Which four statements are correct regarding MSDP configurations and operations? (Choose four.)
A. The MSDP peers are also typically the RPs in respective routing domains.
B. SA messages are flooded to all other MSDP peers without any restrictions
C. On Cisco IOS, IOS-XE, and IOS-XR, the router can be configured to cache the SA messages to reduce the join latency
D. SA messages are used to advertise active sources in a domain
E. MSDP establishes neighbor relationships with other MSDP peers using TCP port 639
F. MSDP peerings on Cisco IOS, IOS-XE, and IOS-XR support MD5 or SHA1 authentication
Answer: ACDE
QUESTION 93
What are three BGP configuration characteristics of a multihomed customer that is connected to multiple service providers? (Choose three.)
A. The multihomed customer can use local preference to influence the return traffic from the service providers
B. The multihomed customer announces its assigned IP address space to its service providers through BGP
C. The multihomed customer has to decide whether to perform load sharing or use a primary/backup implementation
D. The multihomed customer must use private AS number
E. The multihomed customer configures outbound route filters to prevent itself from becoming a transit AS
Answer: BCE
QUESTION 94
Refer to the configuration exhibit, taken from a Cisco IOS-XR router.
Which configuration change is required to properly enable this router as the signaling router for implementing source-based RTBH filtering?
A. Set community (no-export) in the route policy
B. Pass in the route policy
C. Set local-preference 1000 in the route policy
D. The 192.0.2.1/32 static route should be tagged as 666 (tag 666)
Answer: A
QUESTION 95
Which command set is used to configure BFD support for a BGP neighbor that is reachable through GigabitEthernet 0/0/0/0 on Cisco IOS XR?
A. router bgp 300
bfd multiplier 2
bfd minimum-interval 20
neighbor 10.20.20.2
remote-as 200
B. router bgp 300
bfd multiplier 2
bfd minimum-interval 20
neighbor 10.20.20.2
remote-as 200
bfd fast-detect
C. bfd
echo disable
router bgp 300
neighbor 10.20.20.2
remote-as 200
D. bfd
router bgp 300
neighbor 10.20.20.2
remote-as 200
E. interface Gi0/0/0/0
ipv4 verify unicast source reachable-via rx
router bgp 300
bfd multiplier 2
bfd minimum-interval 20
neighbor 10.20.20.2
remote-as 200
bfd fast-detect
F. interface Gi0/0/0/0
ipv4 verify unicast source reachable-via rx
bfd
interface Gi0/0/0/0
echo disable
router bgp 300
bfd multiplier 2
bfd minimum-interval 20
neighbor 10.20.20.2
remote-as 200
Answer: B
QUESTION 96 
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: AE
Explanation:
#show ip bgp
QUESTION 97
When verifying the BGP neighbor relationships on your router, you issue the show ip bgp summary command and there were no results. Which of the following could be the problem?
A. The TCP session to the BGP neighbor can’t be established.
B. There are no BGP neighbors configured.
C. All BGP updates from the BGP neighbor were filtered out.
D. The neighbor link is down.
Answer: B
QUESTION 98
Which BGP configuration option is designed to reduce router processing load caused by unstable routes?
A. neighbor {ip-address} maximum-prefix {number}
B. bgp dampening
C. no sync
D. bgp deterministic-med
E. sync
F. bgp scan-time
Answer: B
QUESTION 99
Why can using the ip tcp path-mtu-discovery command improve BGP convergence?
A. Single packet sizes in TCP sessions are limited.
B. Smaller MSS sizes may reduce BGP convergence times.
C. BGP is allowed to use a larger TCP window size.
D. BGP is enabled to fragment its large update packets.
E. The BGP memory requirements on routers are reduced.
Answer: B
QUESTION 100
Which two of the following are true regarding the BGP Prefix-Based outbound route filtering feature? (Choose two.)
A. IP multicast routes are not supported.
B. Outbound route filtering is configured only on a per-address family basis.
C. Outbound route filtering can be configured for either iBGP or eBGP sessions.
D. The outbound route filter can be defined in a Prefix list, Distribute list or Access lists.
E. Outbound route filtering is more effective when a distance vector IGP is used.
Answer: AB
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