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Exam A
QUESTION 1
For which purpose is the command mpls ldp maxhops used?
A. In large ATM-MPLS networks, the LFIB can become too large and it may be necessary to limit the maximum diameter of the MPLS LSPs.
B. Because downstream-on-demand label allocation uses hop count to control loop detection, it maybe necessary to limit the maximum diameter of the MPLS network.
C. Because end-to-end delay can cause problems with some voice applications, it may be necessary to limit the maximum diameter of the MPLS network.
D. When interconnecting large frame mode MPLS and cell mode networks it may be necessary to limit the maximum network diameter to prevent forwarding loops.
Correct Answer: B Section: (none) Explanation
Explanation/Reference:
QUESTION 2
Refer to the diagram. What problem can be caused by the second P router summarizing the loopback address of the egress PE router?
A. The first P router will be faced with a VPN label which it does not understand.
B. The second P router will be faced with a VPN label which it does not understand.
C. The egress PE router will not be able to establish a label switch path (LSP) to the ingress PE router.
D. A label switch path (LSP) will be established from the ingress PE router to the egress PE router, an event that is not desirable.
E. The ingress PE router will not be able to receive the VPN label from the egress PE router via MP-IBGP.
Correct Answer: B Section: (none) Explanation
Explanation/Reference: QUESTION 3
In a central services topology, which routes do client VRFs contain?
A. routes from the client site, but not from the server site
B. routes from the server site, but not from the client site
C. routes from both the client site and the server site
D. only EBGP routes from either the client site or the server site
Correct Answer: C Section: (none) Explanation
QUESTION 4
On a dedicated subinterface implementation, PE-2 must establish an address-family vrf IPv4 BGP neighbor relationship with which router?
A. CE-1
B. CE-2
C. PE-1
D. PE-IG
E. CE-1 and CE-2
F. PE-1 and PE-IG
Correct Answer: B Section: (none) Explanation
Explanation/Reference: QUESTION 5
What are three drawbacks of a peer-to-peer VPN using a shared provider edge (PE) router? (Choose three.)
A. A full mesh of virtual circuits is required between the customer sites.
B. All the customers have to share a common IP address space.
C. Optimal routing between customer sites cannot be guaranteed.
D. The shared PE router has to know all routes for all customers.
E. Packet filters are required on the PE routers.
Correct Answer: BDE Section: (none) Explanation
QUESTION 6
Which two of the following statements regarding LDP are true? (Choose two.)
A. LDP can also be used between nonadjacent routers using multicast LDP hello messages.
B. LDP does not require periodic hello messages once the LDP session has been established between the LDP peers.
C. LDP hello messages use TCP packets with a destination port number of 646.
D. Multiple sessions can be established between a pair of LSRs if they use multiple label spaces.
E. Per-platform label space can be identified by a label space ID of 0 in the LDP identifier field.
Correct Answer: DE Section: (none) Explanation
Explanation/Reference:
QUESTION 7
Refer to the exhibit. Which two of the following statements about the MPLS configurations are true? (Choose two.)
A. The VPI range being configured is the default VPI range.
B. The router is missing the mpls label protocol ldp configuration command on its ATM 0/0.1 subinterface to make it an LC-ATM enabled subinterface.
C. There is a problem with the configurations because the control VC should be set to 0 32 instead.
D. The ATM switch is using VC merge since VC merge is enabled by default.
E. For MPLS label allocations, both VPI 6 and 7 can be used.
Correct Answer: DE Section: (none) Explanation
QUESTION 8
What does the following command accomplish? sanjose#clear ip bgp 10.1.1.1 in prefix-filter
A. The sanjose router will perform an outbound soft reconfig to the 10.1.1.1 neighbor.
B. The sanjose router will send out the ORF prefix-list so that a new route refresh will be received from the
1.1.1 neighbor.
C. The 10.1.1.1 router will perform an inbound soft reconfig on the updates from the sanjose neighbor.
D. The 10.1.1.1 router will send out the ORF prefix-list so that a new route refresh will be received from the sanjose neighbor.
E. The bgp session between the sanjose and the 10.1.1.1 router will be reset so that all the new bgp updates from the 10.1.1.1 router can be processed by the inbound prefix-list at the sanjose router.
F. The bgp session between the sanjose and the 10.1.1.1 router will be reset so that all the new bgp updates from the sanjose router can be processed by the inbound prefix-list at the 10.1.1.1 router.
Correct Answer: B Section: (none) Explanation
Explanation/Reference:
QUESTION 9
Based on the topology diagram shown in the exhibit, when should BGP be used as the routing protocol between the customer and the ISP?
A. If physical link failures can not be detected by the link-level procedures.
B. If the customer wants to affect how the ISP will route the customer’s traffic out to the rest of the Internet.
C. If the ISP does not support static routing with the customer.
D. If the customer is using provider-assigned (PA) addresses inside the customer’s network.
E. If the customer is using private addresses inside the customer’s network.
Correct Answer: A Section: (none)
Explanation
QUESTION 10
Based on the network diagram shown in the exhibit, what is the correct configuration on the customer edge router used to conditionally announce the customer networks to the ISP?
A. router bgp 65001 ! neighbor commands not shown network 192.168.8.0 mask 255.255.252.0 ! ip route 192.168.8.0 255.255.252.0 192.168.8.33
B. router bgp 65001 ! neighbor commands not shown aggregate-address 192.168.8.0 255.255.252.0 summary-only ! ip route 192.168.8.0 255.255.252.0 192.168.8.33
C. router bgp 65001 ! neighbor commands not shown network 192.168.8.0 network 192.168.9.0 network 192.168.10.0 network 192.168.11.0 ! ip route 192.168.8.0 255.255.255.0 null0 ip route 192.168.9.0 255.255.255.0 null0 ip route 192.168.10.0 255.255.255.0 null0 ip route 192.168.11.0 255.255.255.0 null0
D. router bgp 65001 ! neighbor commands not shown aggregate-address 192.168.8.0 255.255.252.0 summary-only ! router ospf 1 network 192.168.8.0 0.0.3.255 area 0
E. router bgp 65001 ! neighbor commands not shown aggregate-address 192.168.8.0 255.255.252.0 ! ip route 192.168.8.0 255.255.252.0 null0
Correct Answer: A Section: (none) Explanation
Explanation/Reference:
QUESTION 11
Which two statements about a transit AS are correct? (Choose two.)
A. A transit AS has eBGP connection(s) to only one external AS.
B. Routes between ASs are always exchanged via eBGP.
C. A transit AS uses an IGP like OSPF or ISIS to propagate the external networks within the transit AS.
D. Core routers within a transit AS normally use default routing to reach the external networks.
E. iBGP sessions can be established between non directly connected routers.
Correct Answer: BE Section: (none) Explanation
QUESTION 12
Based on the network diagram shown in the exhibit, both R5 and R6 are clients of the R2 RR. When the 0.0.0/8 iBGP update from R3 is received by the R2 RR, which router(s) will R2 reflect the update to?
A. R1 only
B. R5 and R6
C. R5, R6 and R1
D. R4, R5 and R6
E. R4, R5, R6 and R1
F. to no other router
Correct Answer: C Section: (none) Explanation
Explanation/Reference:
QUESTION 13
Which show command can be used to display the originator ID and cluster-list?
A. show ip bgp
B. show ip bgp sum
C. show ip route bgp
D. show ip route {prefix}
E. show ip bgp {prefix}
F. show ip bgp neighbors {ip address}
Correct Answer: E Section: (none) Explanation
Explanation/Reference:
QUESTION 14
Which command is used to configure the external, confederation-wide AS number?
A. router(config)#router bgp {as-number}
B. router(config-router)#bgp confederation peers {as-number}
C. router(config-router)#bgp confederation identifier {as-number}
D. router(config-router)#bgp cluster-id {as-number}
E. router(config-router)#neighbor {ip address} remote-as {as-number}
Correct Answer: C Section: (none) Explanation
QUESTION 15
As the penalty for a flapping route decreases and falls below a certain limit, the route is unsuppressed. What is the name of that limit?
A. half-life limit
B. suppress limit
C. max-suppress-time limit
D. reuse limit
E. unsuppress limit
F. penalty limit
Correct Answer: D Section: (none) Explanation
Explanation/Reference: QUESTION 16
What is the difference in implementation between a managed CE services MPLS VPN and a central services MPLS VPN?
A. RD assignment
B. selective routes export
C. selective routes import
D. MP-BGP route redistribution filtering
E. CE-PE routing process
F. none
Correct Answer: B Section: (none) Explanation
Explanation/Reference:
QUESTION 17
In a Transit AS, how do the internal routers within the Transit AS forward packets destined for the external networks using a scalable solution?
A. using the default route
B. using the IGP routes where the external networks are redistributed into the IGP by the edge routers
C. using the EBGP routes where the external networks are redistributed into the IBGP by the edge routers
D. using the IBGP routes, then using recursive lookup based on IGP information to resolve the BGP next-hop
Correct Answer: D Section: (none) Explanation
Explanation/Reference:
QUESTION 18
Given the following configurations, R2 and R3 are not able to successfully establish the IBGP session using the loopback 0 interfaces. What could be the cause of this problem?
! output omitted
!
hostname R2 ! interface loopback 0 ip address 2.2.2.2 ! interface e0 ip address 10.1.1.1 255.255.255.0 no shut ! interface e1 ip address 10.2.2.1 255.255.255.0 no shut ! router bgp 65101 neighbor 172.16.1.1 remote-as 65100 neighbor 3.3.3.3 remote-as 65101 ! router eigrp 101 network 10.0.0.0 network 2.0.0.0 ! !
! output omitted !
hostname R3 ! interface loopback 0 ip address 3.3.3.3 ! interface e0 ip address 10.1.1.2 255.255.255.0 no shut ! interface e1 ip address 10.2.2.2 255.255.255.0 no shut ! router bgp 65101 neighbor 192.168.1.1 remote-as 65102 neighbor 2.2.2.2 remote-as 65101 ! router eigrp 101 network 10.0.0.0 network 3.0.0.0 !
A. The “No Sync” BGP configuration command is missing.
B. R2 and R3 are not using the loopback0 IP address as the source address for the BGP messages to each other.
C. The “network 2.0.0.0” BGP configuration command is missing on R2 and the “network 3.0.0.0” BGP configuration command is missing on R3.
D. The “neighbor 2.2.2.2 ibgp-multihop 2” BGP configuration command is missing on R3 and the “neighbor 3.3.3.3 ibgp-multihop 2” BGP configuration command is missing on R2.
Correct Answer: B Section: (none) Explanation
Explanation/Reference:
QUESTION 19
AS-Path prepending is used in AS1 in order to influence the return traffic path from AS 5 to AS 1 through the higher speed path via AS 2. _____ needs to be configured for AS-Path prepending and a minimum of _____ of the AS number should be prepended.
A. R1; one copy
B. R2; one copy
C. R1; two copies
D. R2; two copies
E. R2; three copies
Correct Answer: C Section: (none) Explanation
Explanation/Reference:
QUESTION 20
In a multihomed environment with two ISP connections, which two statements are true? (Choose two.)
A. The customer should not be configured to act as a transit AS between the two ISPs.
B. It is recommended that the multi-homed customer use a registered (public) AS number.
C. AS-Path prepending can be configured on the customer’s edge router to influence the BGP path selection process for the outbound traffic (traffic from the customer to the ISPs).
D. The customer can use Local Preference on the customer’s edge routers to influence the BGP path selection process for the inbound traffic (traffic from the ISPs to the customer).
E. The advertisement of the customer’s IP address space can be conditioned by the customer’s edge routers by using a static route to the null0 interface and by using the proper network statement under router bgp.
Correct Answer: AB Section: (none) Explanation
Explanation/Reference:
This volume is part of the Exam Certification Guide Series from Cisco 642-691.Cisco 642-691 in this series provide officially developed exam preparation materials that offer assessment, review, and practice to help Cisco 642-691 Certification candidates identify weaknesses,concentrate their study efforts,and enhance their confidence as Cisco 642-691 exam day nears.