SPCORE question of the day

[PlAwAnSaI]

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 copy the decremented IP TTL field into the MPLS Label TTL field.

B. 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.

C. 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.

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 IP TTL field by 1.

E. When an ingress edge LSR receives an IP packet, it will just copy the IP TTL field into the MPLS Label TTL field.

 

[PlAwAnSaI]

Which three statements are correct regarding ping mpls command operations?

A. They are used to test for a broken LSP.

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. 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.

E. MPLS OAM has to be enabled on the router using the mpls oam command.

 

[PlAwAnSaI]

What are the four fields inside the MPLS shim header?

A. Type

B. Label

C. S

D. TTL

E. FCS

F. Version

G. EXP

H. Length

 

[PlAwAnSaI]

Which two of the following statements are correct regarding LSPs?

A. Each LSP is bidirectional, that is, packets traveling in the opposite direction use the same LSP.

B. An LSP is created for every routing protocol entry.

C. The FIB is used to forward MPLS-labeled packets down an LSP.

D. An IGP is used to populate routing tables in all routers in an MPLS domain.

E. LDP is used to propagate labels and build LSPs.

 

[PlAwAnSaI]

Which four pieces of information are stored for each prefix in the LFIB?

A. next-hop IP address

B. Layer 2 header rewrite information

C. outgoing label

D. outgoing interface

E. incoming interface

F. local label

 

[PlAwAnSaI]

Which three network services can be implemented using MPLS within the service provider IP NGN core?

A. IntServ traffic engineering tunnels

B. Layer 2 VPNs

C. Layer 3 VPNs

D. encrypted LSPs

E. traffic engineering

 

[PlAwAnSaI]

LDP session protection uses which one to maintain the LDP session between LDP neighbors?

A. LDP-IGP synchronization

B. BFD

C. backup-targeted LDP hellos

D. LDP NSR

E. LDP NSF

 

[PlAwAnSaI]

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 interface all command under the MPLS LDP process

B. use the mpls ldp sync command under the IGP routing precess

C. use the discovery command under the MPLS LDP process

D. use the mpls ldp auto-config command under the IGP routing process

 

[PlAwAnSaI]

Which two statements are correct in describing ISP environments that are running IP/MPLS in the core network?

A. The PE and P routers run LDP to learn the labels for reaching the BGP next-hop addresses.

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. On the PE routers, each BGP route must use a unique label to reach the BGP next hop.

 

[PlAwAnSaI]

When troubleshooting LDP operations on the Cisco IOS and IOS XE routers, what is one of the first things that should be verified?

A. check if the ip cef command has been enabled

B. if running OSPF as the IGP, ensure that OSPFv3 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

 

[PlAwAnSaI]

Referring to the Cisco IOS XR configuration exhibit,

mpls ldp
label
advertise
disable
for test1 to test2
!
ipv4 access-list test2
10 permit ipv4 any any
ipv4 access-list test1
10 permit ipv4 host 10.1.1.1 any

which labels will be advertised by the router with this configuration?

A. Only the label for 10.1.1.1/32 will be advertised to all the LDP peers.

B. No labels will be advertised to any LDP peers.

C. Labels for all prefixes will be advertised to the 10.1.1.1 LDP peer.

D. Labels for all prefixes will be advertised to all the LDP peers.

 

[PlAwAnSaI]

What is the term that is used for the label that an LSR assigns and distributes to other LSRs in MPLS?

A. Aggregate

B. Explicit

C. Remote

D. Explicit Null

E. Local

 

[PlAwAnSaI]

Which Cisco IOS XR high-availability feature is used to prevent routes from being used before LDP converges?

A. IGP session protection

B. BFD

C. LDP session protection

D. LDP-IGP synchronization

 

[PlAwAnSaI]

Which Cisco IOS XR command should be used in order to enable LDP-IGP synchronization for the ISIS IGP protocol?

A. RP/0/RSP0/CPU0:R1(config-ldp)#isis ldp sync

B. RP/0/RSP0/CPU0:R1(config-isis-if-af)#mpls ldp sync

C. RP/0/RSP0/CPU0:R1(config-isis)#mpls ldp sync

D. LDP-IGP synchronization is not supported for the ISIS IGP protocol on Cisco IOS XR platforms

 

[PlAwAnSaI]

Referring to the Cisco IOS XR show command output exhibit,

RP/0/RSP1/CPU0:ASR9006#sh mpls ldp igp sync
Bundle-Ether9000:
Sync status: Ready
Peers:
192.168.1.25:0 (GR)
GigabitEthernet0/1/0/10:
Sync status: Not ready

what are three possible reasons that the GigabitEthernet0/1/0/10 LDP IGP sync status is not ready?

A. The OSPF neighbor on GigabitEthernet0/1/0/10 is not up.

B. LDP is up on GigabitEthernet0/1/0/10, but no label bindings have been received from the peer.

C. GigabitEthernet0/1/0/10 is not configured to run LDP.

D. The LDP neighbor on GigabitEthernet0/1/0/10 is not up.

E. Graceful restart is not configured on the peer.

F. GigabitEthernet0/1/0/10 is a member link of Bundle-Ether9000.

 

[PlAwAnSaI]

In which two Cisco IOS XR configuration modes can mpls ldp igp sync be configured?

A. config-isis

B. config-ospf

C. config-ldp

D. config-if

E. config-ospf-ar

 

[PlAwAnSaI]

On Cisco routers, which three methods can be used to map traffic into the MPLS traffic engineering tunnel?

A. static routing

B. optimized edge routing

C. autoroute

D. on-demand routing

E. policy-based routing

 

[PlAwAnSaI]

Which three statements are correct regarding a Cisco MPLS TE?

A. CBR takes into account link resource and traffic tunnel attributes.

B. A Cisco MPLS TE tunnel maps onto an LSP path.

C. RSVP is used between customer routers.

D. A tunnel that is created with a priority of 0 can pre-empt an existing tunnel with a priority of 7.

E. Packets that are mapped into a Cisco MPLS TE tunnel will have two labels, with the top label indicating what the tail-end router should do with the packet.

F. Tunnels are bidirectional by default.

 

[PlAwAnSaI]

On a Cisco router, when will the router actually reserve the bandwidth for the MPLS traffic engineering tunnel?

A. on the receipt of the RSVP Resv message

B. during the autoroute process

C. on the receipt of the RSVP Path message

D. during constraint-based routing calculations

 

[PlAwAnSaI]

Cisco MPLS TE path setup can be affected by which three tunnel attributes?

A. MTU

B. delay

C. affinity

D. bandwidth

E. priority