QUESTION 21
Which statement is correct regarding the default MPLS TTL behavior?
A. When an ingress edge LSR receives an IP packet, it will decrement the IP TTL field by 1; then it will set the MPLS Label TTL field to 255.
B. When an ingress edge LSR receives an IP packet, it will decrement the IP TTL field by 1; then it will copy the decremented IP TTL field into the MPLS Label TTL field.
C. When an ingress edge LSR receives an IP packet, it will just copy the IP TTL field into the MPLS Label TTL field.
D. When an ingress edge LSR receives an IP packet, it will copy the IP TTL field into the MPLS Label TTL field first; then it will only decrement the MPLS Label TTL field by 1.
E. When an ingress edge LSR receives an IP packet, it will copy the IP TTL field into the MPLS Label TTL field first; then it will only decrement the IP TTL field by 1.
Answer: B
QUESTION 22
Which three statements are correct regarding ping mpls command operations? (Choose three.)
A. MPLS OAM has to be enabled on the router using the mpls oam command.
B. They use a 127/8 address as the destination address in the MPLS echo request packet.
C. They use ICMP echo request and ICMP echo reply packets.
D. They are used to test for a broken LSP.
E. If there is a broken LSP, instead of using label switching, the packet can still be forwarded based on the destination IP address in the mpls ping echo request packet.
Answer: ABD
QUESTION 23
When a link flaps, an mpls ldp session will also flap. Which feature minimizes traffic loss and provides faster convergence after the link is re-established?
A. BFD
B. MPLS LDP IGP SYNC
C. graceful restart
D. LDP session protection
E. LDP nonstop routing
Answer: D
QUESTION 24
A DSCP value of 41 in decimal corresponds to which IP precedence value?
A. 3 – Flash
B. 4 – Flash Override
C. 5 – Critical
D. 6 – Internet Control
E. 7 – Network Control
Answer: C
QUESTION 25
Which four pieces of information are stored for each prefix in the LFIB? (Choose four.)
A. local label
B. outgoing label
C. next-hop IP address
D. outgoing interface
E. incoming interface
F. Layer 2 header rewrite information
Answer: ABCD
QUESTION 26
Which three network services can be implemented using MPLS within the service provider IP NGN core? (Choose three.)
A. Layer 2 VPNs
B. Layer 3 VPNs
C. traffic engineering
D. IntServ traffic engineering tunnels
E. encrypted LSPs
Answer: ABC
QUESTION 27
LDP session protection uses which one to maintain the LDP session between LDP neighbors?
A. LDP NSF
B. LDP NSR
C. backup-targeted LDP hellos
D. BFD
E. LDP-IGP synchronization
Answer: C
QUESTION 28
You are tasked to enable LDP on many of the interfaces on the Cisco CRS-3 router, and because there are many interfaces that need to have LDP enabled, you mistakenly did not enable LDP on all the required interfaces. To prevent this issue from happening again in the future, what could you do the next time you need to enable LDP on many interfaces?
A. use the mpls ldp auto-config command under the IGP routing process
B. use the mpls ldp sync command under the IGP routing process
C. use the interface all command under the MPLS LDP process
D. use the discovery command under the MPLS LDP process
Answer: A
QUESTION 29
Which two statements are correct in describing ISP environments that are running IP/MPLS in the core network? (Choose two.)
A. On the PE routers, each BGP route must use a unique label to reach the BGP next hop.
B. The BGP next hops point to the PE routers, and only the PE routers are required to run BGP.
C. A full mesh of IBGP sessions are required between all of the PE and P routers to ensure proper packets forwarding.
D. The PE and P routers run LDP to learn the labels for reaching the BGP next-hop addresses.
Answer: BD
QUESTION 30
When troubleshooting LDP operations on the Cisco IOS and IOS XE routers, what is one of the first things that should be verified?
A. if running OSPF as the IGP, ensure that OSPFv3 has been enabled
B. check if the ip cef command has been enabled
C. verify in the running configurations that all of the required LDP interfaces are defined under the mpls ldp command configuration mode
D. verify if there are any access lists that are denying TCP and UDP port 464 packets
Answer: B
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