Nokia 4A0-116 Exam Questions Instant Access

Question 1

In which of the following aspects does the configuration of flex-algo LSPs have an advantage over the configuration of SR-TE LSPs?

ALabel stack size of the encapsulated data packets

BList of traffic-engineering constraint types available to choose from

CAbility to associate one primary and up to two secondary paths to the same LSP

DFlexibility of configuring each LSP with its own set of traffic-engineering constraints

Answer : D

Flex-Algo LSPs are a type of LSP that allows for greater flexibility in configuring traffic engineering constraints. This is because flex-algo LSPs can be configured with a unique set of traffic engineering constraints for each LSP, whereas SR-TE LSPs use a predefined set of traffic engineering constraints that applies to all LSPs.

Label stack size of the encapsulated data packets, List of traffic-engineering constraint types available to choose from, and Ability to associate one primary and up to two secondary paths to the same LSP are not the advantages of flex-algo LSPs over SR-TE LSPs.

Question 2

Which of the following statements about primary and secondary SR-TE LSP paths is FALSE?

AOnly one LSP path forwards the traffic at any time,

BUp to three paths can be configured for a given SR-TE LS

CThe primary path is always preferred over a secondary pa

DPreference values can be configured for non-standby secondary paths.

Answer : B

Typically, in SR-TE, only two paths can be configured for a given SR-TE LSP: primary path and secondary path. The primary path is used for normal traffic forwarding, and the secondary path is used as a backup in case the primary path fails. Only one LSP path forwards the traffic at any time.

Question 3

Which of the following is NOT a valid option to steer traffic into a flex-algo segment-routing tunnel?

AUsing a flex-algo Node-SID as an explicit hop in the path definition of an SR-TE LSP and enabling the sr-te tunnel type for a VPN service.

BSpecifying the flex-algo instance ID as an additional TE constraint for an SR-TE LSP and enabling the sr-te tunnel type for a VPN service.

CConfiguring and applying a VRF import policy to a VPRN service and enabling the sr-is-is or sr-ospf tunnel type for the service, depending on the underlying routing protocol.

DConfiguring and applying a VSI import policy to an EVPN service and enabling the sr-is-is or sr-ospf tunnel type for the service, depending on the underlying routing protocol.

Answer : D

Applying a VSI import policy to an EVPN service and enabling the sr-is-is or sr-ospf tunnel type for the service is not a valid option for steering traffic into a flex-algo segment-routing tunnel, VSI is not related to flex-algo SR.

Question 4

Which of the following is an advantage of enabling label stack reduction for a CSPF-calculated path, as compared to using plain CSPF?

AThe number of hops included in the end-to-end path is reduced.

BThe path calculation can be delegated to an external path computation element (PCE).

CThere is a larger list of traffic-engineering constraint types that can be imposed on the LSP path.

DThe routers in the calculated path can take advantage of ECMP to better distribute the traffic load.

Answer : A

Once a path is associated with an LSP, it cannot be used by other LSPs is False. A path can be used by multiple LSPs, but each LSP can have different attributes like bandwidth, priority and other constraints.

Question 5

Based on the exhibit, which of the following statements about fast re-route for flex-algo instance 129 is TRUE?

AOnly standard LFA is enabled on router R1; fast re-route is not enabled on router R2.

BOnly standard LFA is enabled on both routers R1 and R2.

CStandard LFA and remote-LFA are enabled on router R1; fast re-route is not enabled on router R2.

DStandard LFA and remote-LFA are enabled on router R1; standard LFA and TT-LFA are enabled on router R2.

Answer : C

Question 6

An SR-TE LSP with a path definition that includes router R4 as a loose hop and for which Seamless-BFD has been enabled is following the path shown in the exhibit. What happens after router R4 fails if the routers along the path follow the default behavior?

AThe head end will periodically try to calculate a new path at a rate defined by the retry timer.

BThe head end will periodically try to calculate a new path at a rate defined by the resignal timer.

CThe head end will continue forwarding traffic to the current next-hop indefinitely, which will be discarded at the point of failure.

DThe head end will continue forwarding traffic to the current next-hop indefinitely, and R2 will redirect the traffic to R3 after IGP reconvergence.

Answer : C

When an SR-TE LSP with Seamless-BFD enabled, the BFD sessions are established between the routers along the path to detect any failures quickly. If a failure happens in the path, the router will stop forwarding the traffic and send a BFD control packet to the head-end router. In this case, R4 failed, BFD sessions will detect the failure and send a message to the head-end router, but since R4 is a loose hop, the path doesn't have to be re-calculate. The head-end router will continue forwarding traffic to the current next-hop, R2, which will be discarded at the point of failure (R4) as it doesn't know about the failure. And the traffic will not be redirected to R3 after IGP reconvergence.

Question 7

For any of the LFA methods to work properly, there must be a router in the backup path that will forward traffic addressed to the destination without sending it back to the source. Which of the following statements describes the way R-LFA selects such a router?

AIt selects an immediate neighbor.

BIt selects a remote router, reachable through a tunnel defined by a single Node-SID.

CIt selects a remote router, reachable through a tunnel defined by a Node-SID and one or two Adjacency-SIDs.

DIt can select an immediate neighbor or a remote router, as long as the backup path coincides with the path that will become active after IGP reconvergence.

Answer : D

R-LFA (Remote Loop-Free Alternate) is a method that can select either an immediate neighbor or a remote router to be used as a backup next hop, as long as the backup path coincides with the path that will become active after IGP reconvergence.

Nokia Segment Routing 4A0-116 Exam Questions