Ensurepass

QUESTION 111

Which of the following statements is correct regarding PIM Sparse Mode operations?

 

A.

Receivers are “registered” with RP by their first-hop router

B.

It supports shared trees only assuming all hosts want the multicast traffic

C.

From the RP, traffic flows down a Source Tree to each receiver

D.

It does not support all underlying unicast routing protocols like BGP

E.

Receivers are “joined” to the Shared Tree (rooted the rp) by their local Designated Router (DR)

 

Correct Answer: E

 

 

QUESTION 112

Which three statements about the Cisco MPLS TE Fast Reroute (FRR) process are true? (Choose three.)

 

A.

TE tunnels that are configured with the FRR option cannot be used as backup tunnels.

B.

TE tunnels that are configured with the FRR option can be used as backup tunnels.

C.

The backup tunnel that is used to protect a physical interface must have a valid IP address configured.

D.

Interfaces must use MPLS global label allocation.

E.

The source IP address of use backup tunnel and the merge point (MP) should not be reachable.

 

Correct Answer: ACD

Explanation:

Restrictions for MPLS Traffic Engineering – Fast Reroute Link and Node Protection

Interfaces must use MPLS Global Label Allocation.

Backup tunnel headend and tailend routers must implement FRR as described in draftpan-rsvp-fastreroute-00.txt.

Backup tunnels are not protected. If an LSP is actively using a backup tunnel and the backup tunnel fails, the LSP is torn down.

LSPs that are actively using backup tunnels are not considered for promotion. If an LSP is actively using a backup tunnel and a better backup tunnel becomes available, the active

LSP is not switched to the better backup tunnel.

You cannot enable FRR Hellos on a router that also has Resource Reservation Protocol (RSVP) Graceful Restart enabled.

(Applicable only to Release 12.2.) You cannot enable primary one-hop autotunnels, backup autotunnels, or autotunnel mesh groups on a router that is also configured with stateful switchover (SSO) redundancy. This restriction does not prevent an MPLS TE tunnel that is automatically configured by TE autotunnel from being successfully recovered by any midpoint router along the LSP’s path if the router experiences an SSO switchover.

MPLS TE LSPs that are fast reroutable cannot be successfully recovered if the LSPs are FRR active and the Point of Local Repair (PLR) router experiences an SSO.

When SSO (stateful switchover) occurs on a router, the switchover process must complete before FRR (fast reroute) can complete successfully. In a testing environment, allow approximately 2 minutes for TE SSO recovery to complete before manually triggering FRR.

To check the TE SSO status, use the show ip rsvp high availability summary command.

Note the status of the HA state field.  When SSO is in the process of completing, this field will display ‘Recovering’.  When the SSO process has completed, this field will display ‘Active’.

 

 

QUESTION 113

DRAG DROP

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Correct Answer:

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QUESTION 114

Which two statements about RPF checks in Multicast Source Discovery Protocol (MSDP) are true? (Choose two)

 

A.

RPF check should be done against the route to the source of the corresponding PIM-SM domain.

B.

Checking session advertisement (SA) messages causes messages looping.

C.

The RPF check ensures that there is a working redundancy for anycast RPs.

D.

RPF check should be done against the route to the RP of the PIM-SM domain that originated the SA.

E.

It prevents message looping, and session advertisement (SA) messages must be RPF checked.

 

Correct Answer: DE

Explanation:

SA Message Receipt

SA messages are only accepted from the MSDP RPF peer that is in the best path back toward the originator.

The same SA message arriving from other MSDP peers must be ignored or SA loops can occur.

Deterministically selecting the MSDP RPF peer for an arriving SA message requires knowledge of the MSDP topology. However, MSDP does not distribute topology information in the form of routing updates. MSDP infers this information by using (M)BGP routing data as the best approximation of the MSDP top
ology for the SA RPF check mechanism. An MSDP topology, therefore, must follow the same general topology as the BGP peer topology. Besides a few exceptions (such as default MSDP peers and MSDP peers in MSDP mesh groups), MSDP peers, in general should also be (M)BGP peers.

Rule 1 of RPF checking in MSDP is applied when the sending MSDP peer is also an i(M)BGP peer. When Rule 1 is applied, the RPF check proceeds as follows:

The peer searches the BGP Multicast Routing Information Base (MRIB) for the best path to the RP that originated the SA message. If a path is not found in the MRIB, the peer then searches the Unicast Routing Information Base (URIB). If a path is still not found, the RPF check fails.

If the previous search succeeds (that is, the best path is found), the peer then determines the address of the BGP neighbor for this best path, which will be the address of the BGP neighbor that sent the peer the path in BGP update messages.

 

 

QUESTION 115

When IPv6 is deployed by a Service Provider to bring on an IPv6 Enterprise, which transition strategy works the best?

 

A.

Deploy IPv6 at the Edges and tunnel Enterprise through the core

B.

None of the above will work

C.

Deploy IPv6 at Edges and Core at the same time for smooth transition

D.

Deploy IPv6 at the core first and then move to Edges toward the end customer

 

Correct Answer: A

 

 

QUESTION 116

Which three statements about BGP confederation and route reflectors are true? (Choose three)

 

A.

Clusters are used in confederation schemes to avoid loops.

B.

BGP network can have a confederation within a route reflector area.

C.

An internal BGP network cannot have a route reflector within a confederation.

D.

An internal BGP network can have a route reflector within a confederation.

E.

Clusters are used in route reflector schemes to avoid loops.

F.

BGP network cannot have a confederation within a route reflector area.

 

Correct Answer: DEF

 

 

QUESTION 117

Which three statements about anycast RP are true? (Choose three.)

 

A.

MSDP is running between anycast RPs.

B.

Anycast RP provides redundancy and load-sharing capabilities

C.

Multicast BGP is running between anycast RPs.

D.

In anycast RP, two or more RPs are configured with the same multicast IP address on loopback interfaces

E.

In anycast RP, two or more RPs are configured with the same unicast IP address on loopback interfaces

 

Correct Answer: ABE

 

 

QUESTION 118

What is the Cisco IOS default behavior for switching from the shared tree to the shortest path tree in PIM-SM operations?

 

A.

immediately after receiving the first packet on the shared tree for a given (S, G)

B.

after receiving over 1 kb/s traffic on the shared tree for a given (S, G)

C.

10 seconds after receiving the first packet on the shared tree for a given (S, G)

D.

30 seconds after receiving the first packet on the shared tree for a given (S, G)

E.

after receiving over 10 kb/s traffic on the shared tree for a given (S, G)

 

Correct Answer: A

 

 

QUESTION 119

What is periodically multicasted (every 10 seconds) by the DIS on a LAN to ensure IS-IS Link State Database accuracy?

 

A.

IIH

B.

LSP

C.

CSNP

D.

ISH

E.

PSNP

 

Correct Answer: C

Explanation:

On broadcast networks, designated routers send complete sequence number PDU (CSNP) packets to maintain database synchronization. The CSNP interval timer is the number of seconds between transmissions of CNSP packets from this interface.

 

 

QUESTION 120

What bit should be set in the link state PDUs in an IS-IS level-1-2 router to indicate that they are a potential exit point out of the area?

 

A.

ATT (Attached) bit

B.

ABR (Area Border Rorter) bit

C.

PN (Pseudonode) bit

D.

P (Partition) bit

E.

Down bit

F.

IS-Type bit

 

Correct Answer: A

 

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