Guaranteed 642-883 Interactive Bootcamp 2021

NEW QUESTION 1
Which high-availability routing feature requires the neighbor router to support the graceful restart capability?

• A. BFD
• B. NSR
• C. NSF
• D. 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:
•IETF NSF
•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

NEW QUESTION 2
Refer to the OSPF command exhibit.

Which effect does the no-summary command option have?

• A. It will cause area 1 to be able to receive non-summarized inter-area routes.
• B. It will cause area 1 to not receive any inter-area routes and will use a default route to reach networks in other areas.
• C. It will cause area 1 to not receive any external routes and will use a default route to reach the external networks.
• D. It will convert the NSSA area into a NSSA totally stubby area.
• E. It will convert the stubby area into a NSSA.
• F. It will disable OSPF auto-summary.

Answer: B

Explanation:

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NEW QUESTION 3
What are two consequences of having constant link flaps, resulting in the OSPF neighbor adjacencies going up and down repeatedly? (Choose two.)

• A. routes getting into the "Stuck In Active" state
• B. constant flooding of LSAs
• C. OSPF route dampening to occur
• D. many SPF recalculations
• E. routing loops may temporarily be introduced into the network

Answer: BD

NEW QUESTION 4
How can you prevent multihomed customers with connections to two service providers from acting as a transit AS?

• A. Enable BGP synchronization on all the customer routers
• B. Use MED to influence the inbound traffic from the ISPs
• C. Use static routing to the ISPs
• D. Use an AS-path access-list to filter the BGP updates to the ISPs
• E. Use conditional advertisements when sending BGP updates to the ISPs

Answer: D

NEW QUESTION 5
A network engineer must provide support to a very large customer running a flat IS-IS Level 2 network. The engineer is willing to redesign the infrastructure in a multiarea fashion due to the rapid growth of the data traffic and newly-required scaling factors. Which consideration is important when implementing the new IS-IS Level 1 areas?

• A. Two IS-IS Level 1 areas divided by the backbone area require a virtual link to communicate when Level 1/Level 2 intermediate systems are missing.
• B. The default behavior of an IS-IS Level 1 area is equivalent to anOSPF totally stubby area.
• C. An IS-IS Level 1 area will always set a gateway pointing to a backbone router.
• D. An IS-IS Level 1 area provides greater flexibility during the Database Descriptors exchange process.

Answer: B

NEW QUESTION 6
When using the show bgp ipv6 unicast summary command to verify the IPv6 BGP session status with the IPv6 BGP peers, you noticed the "St/PfxRcd" status for one of the IPv6 BGP peers is in the "Active" state. What does the "Active" state indicate?

• A. The IPv6 BGP session has been established with the IPv6 BGP peer.
• B. The router is in the process of sending BGP routing updates to the IPv6 BGP peer.
• C. The router is in the process of establishing the IPv6 BGP session with the IPv6 BGP peer.
• D. The router is exchanging BGP notification messages with its IPv6 BGP peer.

Answer: C

NEW QUESTION 7
Refer to the PE1 router routing table output exhibit.

What is causing the i su 10.1.10.0/24 [115/30] via 0.0.0.0, 00:40:34, Null0 entry on the PE1 router routing table?

• A. The PE1 router is receiving the 10.1.10.0/24 summary route from the upstream L1/L2 IS-IS router.
• B. The PE1 router has been configured to summarize the 10.1.10.x/32 IS-IS routes to 10.1.10.0/24.
• C. The 10.1.10.0/24 has been suppressed because IS-IS auto-summary has been disabled on the PE1 router.
• D. The 10.1.10.0/24 has been suppressed because of a route policy configuration on the PE1 router.
• E. The 10.1.10.0/24 has been suppressed because the more specific 10.1.10.x/32 IS-IS routes have been configured to leak into the IS-IS non-backbone area.

Answer: B

Explanation:

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NEW QUESTION 8
Refer to the topology diagram in the exhibit.

Which IS-IS feature could be implemented so that the return path for the packets from router Y in area 49.00AA to router X in area 49.00BB will use the more optimal path?

• A. Enable route leaking to pass Level 2 information into the Level 1 routers.
• B. Change the area 49.00AA type from a stub area to a regular area.
• C. Change the IS-IS administrative distance on router Y in area 49.00AA.
• D. Change the IS-IS metric type from narrow to wide on all IS-IS routers.

Answer: A

Explanation:
http://www.cisco.com/application/pdf/paws/13796/route-leak.pdf
The ISIS routing protocol allows for a twolevel hierarchy of routing information. There can be multiple Level 1 areas interconnected by a contiguous Level 2 backbone. A router can belong to Level 1, Level 2, or both. The Level 1 linkstate database contains information about that area only. The Level 2 linkstate database contains information about that level as well as each of the Level 1 areas. An L1/L2 router contains both Level 1 and Level 2 databases. It advertises information about the L1 area to which it belongs into L2. Each L1 area is essentially a stub area. Packets destined for an address that is outside of the L1 area are routed to the closest L1/L2 router to be forwarded on to the destination area. Routing to the closest L1/L2 router can lead to suboptimal routing when the shortest path to the destination is through a different L1/L2 router.
Route leaking helps reduce suboptimal routing by providing a mechanism for leaking, or redistributing, L2 information into L1 areas. By having more detail about inter area routes, an L1 router is able to make a better choice with regard to which L1/L2 router to forward
the packet.

NEW QUESTION 9
For a Cisco IOS XR router, under which BGP configuration group can default-originate be added?

• A. session-group
• B. af-group
• C. neighbor-group
• D. peer-session template

Answer: B

NEW QUESTION 10
What is function of the RP/0/RSP0/CPU0:PE1(config-ospf)#distance Cisco IOS-XR command?

• A. To modify the administrative distance of the OSPF routes
• B. To modify the default seed metric of the OSPF external routes
• C. To modify the OSPF default reference bandwidth
• D. To modify the OSPF cost

Answer: A

Explanation:
http://www.cisco.com/en/US/docs/ios_xr_sw/iosxr_r3.8/routing/command/reference/rr38osp f.pdf

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NEW QUESTION 11
On Cisco IOS XR Software, which set of commands is used to enable the gi0/0/0/1 interface for OSPF in area 0?

• A. interface gi0/0/0/0ip address 10.1.1.1 255.255.255.0!router ospf 1network 10.1.1.1 0.0.0.0 area 0
• B. interface gi0/0/0/0ip address 10.1.1.1 255.255.255.0!router ospf 1network 10.1.1.1 255.255.255.255 area 0
• C. router ospf 1 area 0interface GigabitEthernet0/0/0/1
• D. interface gi0/0/0/0ip address 10.1.1.1 255.255.255.0ip ospf 1 area 0
• E. router ospf 1address-family ipv4 unicastinterface GigabitEthernet0/0/0/1 area 0
• F. router ospf 1address-family ipv4 unicast interface GigabitEthernet0/0/0/1 area 0

Answer: C

NEW QUESTION 12
Why would a network engineer want to implement BGP peer groups on Cisco IOS XE routers?

• A. to have a single point of configuration for all route maps used with BGP
• B. to have a single point of configuration for neighbors with the same BGP policies
• C. to have a single point of configuration for all global BGP configurations
• D. to have a single point of configuration for all Layer 3 VPN customer VRFs

Answer: B

NEW QUESTION 13
Which AS path access list is used by a multihomed customer to only announce their own address space to their service providers to prevent the multihomed customer from becoming a transit AS?

• A. ip as-path access-list permit.*
• B. ip as-path access-list permit^$
• C. ip as-path access-list permit _$
• D. ip as-path access-list permit _^
• E. ip as-path access-list permit local-as ip as-path access-list deny *
• F. ip as-path access-list deny.* ip as-path access-list permit *

Answer: B

Explanation:

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NEW QUESTION 14
In Cisco IOS XE, which option is the default threshold value for slow peer detection?

• A. 120 seconds
• B. 180 seconds
• C. 240 seconds
• D. 300 seconds

Answer: D

NEW QUESTION 15
A Network Operation Center requires support to understand OSPFv3 neighborship operations. During a migration, two OSPFv3 routers became adjacent even though no common subnets were configured on the link interfaces. Which statement explains this problem?

• A. This problem is a bug in Cisco IOS XE, which requires a case tobe open with Cisco TAC and an immediate Cisco IOS upgrade to avoid security breaches and rerouting attacks.
• B. IPv6 needs only the link-local address to from an OSPFv3 neighborship.
• C. The Network Operation Center Engineers did not notice a supernet configured on one end of the IPv6 link.
• D. The Network Operation Center Engineers did not add the secondary keyword after the IPv6 address, which causes the router to overwrite the main address.

Answer: B

NEW QUESTION 16
Which option describes the configuration for a Cisco IOS XR OSPF router to give it the highest chances of becoming DR?

• A. ip ospf priority 0 under the OSPF interface statement
• B. ip ospf priority 0 under the OSPF area statement
• C. ip ospf priority 255 under the OSPF interface statement
• D. ip ospf priority 255 under the OSPF area statement
• E. Leave priority unchanged, but assign a high-numbered IP address on a loopback interface.
• F. Leave priority unchanged, but assign a high-numbered IP address on any physical interface.

Answer: C

NEW QUESTION 17
A service provider is deploying route redistributions for a large enterprise that wants to unify a few IGP routing domains into one to condense administration as well as common network and security policies. Which technique should be used to safely assume that the new routing domain is loop free?

• A. Enable filtering based on route-tagging on the redistribution points to avoid route- feedback.
• B. Define a static route to Null0 for all of the outgoing traffic on the redistribution points.
• C. Modify the metric associated with each redistributed prefix to implement loop-avoidance for inter-IGP routing domain designs.
• D. Disable the routing process on the interfaces with route-feedback potential on the redistribution points.

Answer: A

NEW QUESTION 18
When configuring IPv4 and IPv6 IS-IS routing on Cisco IOS XR routers, which three statements are correct? (Choose three.)

• A. By default, a single SPF is used for both IPv4 and IPv6, so the IPv4 and IPv6 topology should be the same.
• B. By default, the IS-IS router type is Level 1 and Level 2.
• C. All IS-IS routers within the same IS-IS area must be configured with the same IS-IS routing process instance ID.
• D. By default, metric-style narrow is used.
• E. By default, the IS-IS interface circuit type is Level 1 and Level 2.
• F. The area IS-IS address-family configuration command is used to specify the IS-IS area address.

Answer: BDE

Explanation:

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The default metric style for single topology is narrow metrics. However, you can use either wide metrics or narrow metrics. How to configure them depends upon how single-topology is configured. If both IPv4 and IPv6 are enabled and single-topology is configured, the metric style is configured in the address-family ipv4 stanza. You may configure the metric style in the address-family ipv6 stanza, but it will be ignored in this case. If IPv6 only is enabled and single topology is configured, then the metric style is configured in the address-family ipv6 stanza.

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NEW QUESTION 19
DRAG DROP

• A. Mastered
• B. Not Mastered

Answer: A

Explanation:
Totally Stubby Area – O,OIA , OE1 or OE2 types of OSPf routes NSSA Totally Stubby – O, and O*IA types of OSPF routes
Stubby OSPF Area - O, OIA and O*IA types of OSPF routes NSSA – O,OIA , ON1 or ON2 types of OSPF Routes

NEW QUESTION 20
Refer to the exhibit.

XR4 must be configured to advertise only AS 100 local subnets to AS 10. Which configuration on XR4 achieves this goal?

• A. as-path-set LOCAL ios-regex ^$route-policy ADVif as-path in LOCAL then pass endif
• B. as-path-set LOCAL ios-regex '^100$' route-policy ADVif as-path in LOCAL then pass endif
• C. as-path-set LOCAL ios-regex '^$'route-policy ADVif as-path in LOCAL then pass endif
• D. as-path-set LOCAL ios-regex ^100$ route-policy ADVif as-path in LOCAL then pass endif

Answer: C

NEW QUESTION 21
Which option is where BGP graceful restart is negotiated between peers?

• A. open message
• B. keep-alive message
• C. notification message
• D. update message

Answer: A

NEW QUESTION 22
A service provider is running BGP with clients at the edge of the network. The service provider sees that routing updates from one site are being dropped when the other site receives them. Which feature fixes this issue?

• A. EBGP multihop
• B. inter-AS peering
• C. AS-override
• D. allow-AS in

Answer: C

NEW QUESTION 23
Which option is a mechanism that can be implemented between two eBGP peers to communicate the routes each peer needs from the other?

• A. ORF
• B. ACL
• C. prefix list
• D. route map

Answer: A

NEW QUESTION 24
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