[Free] 2019(Nov) EnsurePass Cisco 642-883 Dumps with VCE and PDF 31-40

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Question No.31

In Cisco IOS and Cisco IOS XE Software images, when redistributing routes from other routing protocols into OSPF, what is a common reason why some of the routes might not be redistributed into OSPF?

  1. The OSPF external metric type (E1 or E2) is not defined.

  2. The OSPF seed metric is not defined.

  3. The OSPF level (Level 1, Level 2, or Level-1-2) to which the routes will be redistributed into is not

    defined.

  4. The subnets option in the redistribute command is missing.

Answer: D

Question No.32

Refer to the exhibit. R2 wants to filter out only routes originated from AS 300. Which AS path access list should be used?

image

  1. ip as-path access-list 1 deny_300$

  2. ip as-path access-list 1 deny^300_

  3. ip as-path access-list 1 deny ^300$

  4. ip as-path access-list 1 deny_300_

Answer: C

Question No.33

Which type of ISP must rely entirely on other ISPs for Internet transit?

  1. Tier 3

  2. Tier 4

  3. Tier 2

  4. Tier 1

Answer: A

Question No.34

Which series of commands configures area 1 as an OSPF totally stubby area on a Cisco IOS XR router?

  1. router ospfv3 1 router-id 10.10.10.1 area 0

    interface GigabitEthernet 0/0/0/1 area 1

    stub no-summary

    interface GigabitEthernet 0/0/0/2

  2. router ospfv3 1 router-id 10.10.10.1

    default-information originate area 0

    interface GigabitEthernet 0/0/0/1

    area 1 stub

    interface GigabitEthernet 0/0/0/2

  3. ipv6 prefix-list default permit ::0/0 router ospfv3 1

    router-id 10.10.10.1

    default-information originate area 0

    interface GigabitEthernet 0/0/0/1 distribute-list prefix-list default in area 1

    interface GigabitEthernet 0/0/0/2

  4. router ospfv3 1 router-id 10.10.10.1 area 0

    interface GigabitEthernet 0/0/0/1 area 1

    interface GigabitEthernet 0/0/0/2 no-summary

    passive

  5. router ospfv3 1 router-id 10.10.10.1 area 0

interface GigabitEthernet 0/0/0/1 area 1

stub

interface GigabitEthernet 0/0/0/2 default-cost 20

Answer: A

Question No.35

Refer to the exhibit. Which Cisco IOS XE command should be added to this configuration for the BFD protocol to operate successfully?

image

  1. Router1(config-if)#bfd echo Router2(config-if)#bfd echo

  2. Router1(config-ospf-ar-if)#bfd fast-detect Router2(config-ospf-ar-if)#bfd fast-detect

  3. Router1(config-router)#bfd all-interfaces Router2(config-router)#bfd all-interfaces

  4. Router1(config-bfd)#echo-enable Router2(config-bfd)#echo-enable

Answer: C

Question No.36

An engineer is working on routers within AS 100. Which regular expression can be used in an AS path access list to match locally originated routes from AS 100?

A. ^100$

B. ^$

C. _100$ D. ^[0-9]*$ Answer: B

Question No.37

An engineer has two routers multihomed to the Internet via BGP. The first should be the primary path for all outbound traffic and the second should automatically become active in the event the primary goes offline. Which method to configure the routers is the most simple?

  1. Set the local-preference to be higher on the primary router.

  2. Set the local-preference to be lower on the primary router.

  3. Set the MED to be higher on the primary router than the backup.

  4. Set the primary router to have a higher weight than the backup.

Answer: A

Question No.38

Which high-availability routing feature requires the neighbor router to support the graceful restart capability?

  1. BFD

  2. NSR

  3. NSF

  4. MTR

Answer: C

Explanation:

On Cisco IOS XR software, NSF minimizes the amount of time a network is unavailable to its users following a route processor (RP) failover. The main objective of NSF is to continue forwarding IP packets and perform a graceful restart following an RP failover.

When a router restarts, all routing peers of that device usually detect that the device went down and then came back up. This transition results in what is called a routing flap, which could spread across multiple routing domains. Routing flaps caused by routing restarts create routing instabilities, which are detrimental to the overall network performance. NSF helps to suppress routing flaps in NSF-aware devices, thus reducing network instability.

NSF allows for the forwarding of data packets to continue along known routes while the routing protocol information is being restored following an RP failover. When the NSF feature is configured, peer networking devices do not experience routing flaps. Data traffic is forwarded through intelligent line cards while the standby RP assumes control from the failed active RP during a failover. The ability of line cards to remain up through a failover and to be kept current with the Forwarding Information Base (FIB) on the active RP is key to NSF operation.

When the Cisco IOS XR router running IS-IS routing performs an RP failover, the router must perform two tasks to resynchronize its link-state database with its IS-IS neighbors. First, it must relearn the available IS-IS neighbors on the network without causing a reset of the neighbor relationship. Second, it must reacquire the contents of the link-state database for the network. The IS-IS NSF feature offers two options when configuring NSF:

image

IETF NSF

image

Cisco NSF

If neighbor routers on a network segment are NSF aware, meaning that neighbor routers are running a software version that supports the IETF Internet draft for router restartability, they assist an IETF NSF router that is restarting. With IETF NSF, neighbor routers provide adjacency and link-state information to help rebuild the routing information following a failover.

In Cisco IOS XR software, Cisco NSF checkpoints (stores persistently) all the state necessary to recover from a restart without requiring any special cooperation from neighboring routers. The state is recovered from the neighboring routers, but only using the standard features of the IS-IS routing protocol. This capability makes Cisco NSF suitable for use in networks in which other routers have not used the IETF standard implementation of NSF.

Question No.39

The S bit in the MPLS header is used for what purpose?

  1. To indicate the bottom level in the label stack

  2. To indicate if LDP is sync to the IGP

  3. To indicate if LDP is sync to the IGP

  4. To indicate the status of the LSP

Answer: A

Explanation:

image

Question No.40

Refer to the exhibit. R1 is advertising subnets 1.1.1.X/32 via eBGP. XR2 must accept only the first seven subnets in its BGP table. Which configuration must occur on XR2 to meet these parameters?

image

  1. route-policy INBOUND

    if destination in FILTER then pass endifrouter bgp 100

    neighbor 10.10.14.1 address-family ipv4 unicast route-policy INBOUND in

  2. router bgp 100

    neighbor 10.10.14.1 address-family ipv4 unicast route-policy FILTER in

  3. router bgp 100

    neighbor 10.10.14.1 address-family ipv4 unicast route-policy SUBNETS in

  4. route-policy INBOUND

if destination in SUBNETS then pass endifrouter bgp 100

neighbor 10.10.14.1 address-family ipv4 unicast route-policy INBOUND in

Answer: A

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