642-691 - BGP + MPLS Exam

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Example Questions

What best describes the following configuration example of allowas-in? router bgp 100 address-family ipv4 vrf CustomerAneighbor 195.12.4.5 remote-as 123 neighbor 195.12.4.5 activateneighbor 195.12.4.5 allowas-in 2 When using MPLS unicast IP forwarding, what will happen if an LSR receives an incoming labeled packet but the LSR can't find that incoming label in its LFIB? What does the BGP synchronization rule prevent? Which three statements are true about route reflectors? (Choose three.) During the autonomous system number migration process, which BGP feature allows a BGP router to act as a router within one autonomous system to some BGP neighbors but also appear to be in another autonomous system to other neighbors? With MPLS VPN-aware NAT, what additional information is tracked inside the NAT translation table? What state will a BGP session move to immediately after the router sends a BGP Open message to its neighbor? When configuring Internet access from a MPLS VPN using a separate subinterface, which two configurations are required on the PE router? (Choose two.) In a multihomed environment with two ISP connections, which two statements are true? (Choose two.) Which two statements about a transit AS are correct? (Choose two.) What benefit does AToM provide to the service provider's customers? Which three fields must be included in MPBGP updates between PE routers in an MPLS network? (Choose three.) The MPLS VPN provider is using a separate Internet VPN to provide Internet access to its MPLS VPN customers. Currently, all of its customers are not able to access the Internet. The partial provider's CE-Internet router configuration is shown below. Based on the configuration, what could be the cause of the problem? ip route 0.0.0.0 0.0.0.0 10.1.1.1 ! router bgp 51001 network 0.0.0.0 neighbor 10.2.2.2 remote-as 51002 ! PE neighbor router neighbor 10.2.2.2 prefix-list test1 out neighbor 10.3.3.3 remote-as 51001 ! Another Internet router neighbor 10.3.3.3 prefix-list test2 out ! ip prefix-list test2 permit 0.0.0.0/0 ip prefix-list test1 permit 0.0.0.0/0 ge 1 Who should use private AS numbers? In a Transit AS, how do the internal routers within the Transit AS forward packets destined for the external networks using a scalable solution? Based on the following show ip bgp neighbors 2.2.2.2 output, which two statements are true? (Choose two.) R1#show ip bgp neighbors 2.2.2.2 BGP neighbor is 2.2.2.2, remote AS 102, internal link Index 1, Offset 0, Mask 0x2 BGP version 4, remote router ID 66.0.0.1 BGP state=Established, table version=1, up for 00:14:52 Last read 00:00:52, hold time is 180, keepalive interval is 60 seconds Minimum time between advertisement runs is 5 seconds Received 233 messages, 0 notifications, 0 in queue Sent 206 messages, 0 notifications, 0 in queue Prefix advertised 0, suppressed 0, withdrawn 0 Connections established 17; dropped 16 Last reset 00:15:02, due to User reset 18 accepted prefixes consume 576 bytes, maximum limit 20 Threshold for warning message 80% 0 history paths consume 0 bytes Which four attributes are used by BGP to detect routing loops? (Choose four.) When configuring Internet access using a separate MPLS VPN, which three statements are correct? (Choose three.) Using MPLS unicast IP forwarding, what will happen if an LSR receives an unlabeled incoming packet? The core routers within a transit AS are running both IBGP and IGP. The edge routers within the transit AS are using the next-hop-self option to establish the IBGP sessions. What can be implemented to improve the routing performance to all external prefixes? What are two purposes of the BGP scan-time command? (Choose two.) In a central services topology, which routes do client VRFs contain? What are three drawbacks of a peer-to-peer VPN using a shared provider edge (PE) router? (Choose three.) Which configuration will enable the R1 router in the AS51003 sub-AS (member-AS) as a route reflector with neighbors 10.1.1.1 and 10.2.2.2 as its route-reflector clients? Which of the following could be called a VPN identifier in the MPLS/VPN architecture? What is the purpose of the global configuration command, ip dhcp relay information option vpn? What is a benefit of CEF switching? What is the correct command to set the BGP scanner interval to two minutes? Which command is used to configure the external, confederation-wide AS number? Which two of the following statements regarding LDP are true? (Choose two.) What best describes the following configuration example of allowas-in? router bgp 100 address-family ipv4 vrf CustomerA neighbor 195.12.4.5 remote-as 123 neighbor 195.12.4.5 activate neighbor 195.12.4.5 allowas-in 2 Which one of these statements regarding intraconfederation EBGP sessions is correct? For which purpose is the command mpls ldp maxhops used? BGP is used as the CE-PE routing protocol in an MPLS VPN. The customer routes are successfully propagated from the CE router to the ingress PE router, but they are not showing up on the egress PE router. What is the most likely cause of the problem?