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QUESTION 40
When using the Cisco IOS XR route policy language to define a logical if-then-else condition, which logical operator has the highest precedence?
A. AND
B. OR
C. NOT
D. IS
E. IN
Correct Answer: C Section: (none) Explanation
Explanation/Reference:
http://www.cisco.com/en/US/docs/ios_xr_sw/iosxr_r3.0/routing/configuration/guide/rc3rpl.html
QUESTION 41
When configuring Cisco IOS XR route policy nesting, which command is used within a route policy to call another route policy?
A. apply
B. continue
C. jump
D. goto
E. call
Correct Answer: A Section: (none) Explanation
Explanation/Reference:
http://www.cisco.com/en/US/docs/ios_xr_sw/iosxr_r3.7/routing/command/reference/rr37plcy.html
Examples
In the following example, the policy CustomerIn applies the route-policy SetLocalPref to conditionally set the local preference on a route. The parameters 20, 30, 40, and 50 are passed to the parameterized policy SetLocalPref, where the local preference is set to:
.
20, if the community 217:20 is present in the route
.
30, if the community 217:30 is present in the route
.
40, if the community 217:40 is present in the route
.
50, if the community 217:50 is present in the route
RP/0/RP0/CPU0:router(config)# route-policy SetLocalPref ($lp0, $lp1, $lp2,
$lp3, $lp4)
RP/0/RP0/CPU0:router(config-rpl)# if community matches-any ($lp0:$lp1)then
RP/0/RP0/CPU0:router(config-rpl-elseif)# set local-preference $lp1
RP/0/RP0/CPU0:router(config-rpl-elseif)# elseif community matches-any
($lp0:$lp2) then
RP/0/RP0/CPU0:router(config-rpl-elseif)# set local-preference $lp2
RP/0/RP0/CPU0:router(config-rpl-elseif)# elseif community matches-any
($lp0:$lp3) then
RP/0/RP0/CPU0:router(config-rpl-elseif)# set local-preference $lp3
RP/0/RP0/CPU0:router(config-rpl-elseif)# elseif community matches-any
($lp0:$lp4) then
RP/0/RP0/CPU0:router(config-rpl-elseif)# set local-preference $lp4
RP/0/RP0/CPU0:router(config-rpl-elseif)# endif
RP/0/RP0/CPU0:router(config-rpl)# end-policy
RP/0/RP0/CPU0:router(config)# route-policy CustomerIn($cust)
RP/0/RP0/CPU0:router(config-rpl)# apply SetLocalPref ($cust, 20, 30, 40, 50)
RP/0/RP0/CPU0:router(config-rpl)# end-policy
RP/0/RP0/CPU0:router(config)# route-policy Cust_217
RP/0/RP0/CPU0:router(config-rpl)# apply CustomerIn(217)
RP/0/RP0/CPU0:router(config-rpl)# end-policy
QUESTION 42
Refer to the Cisco IOS XR route policy exhibit. If the original incoming routing update has an MED of 10 and a local preference of 100, how will the routing update be modified?
A. The local preference will be set to 100, the MED will be set to 10, and the weight will be set to 100.
B. The local preference will be set to 100, the MED will be set to 10, and the weight will be set to 200. “First Test, First Pass” – www.lead2pass.com 18 Cisco 642-883 Exam
C. The local preference will be set to 200, the MED will be set to 10, and the weight will be set to 100.
D. The local preference will be set to 200, the MED will be set to 10, and the weight will be set to 200.
Correct Answer: C Section: (none) Explanation
QUESTION 43
What is defined by using the Cisco IOS XR policy-global configuration command?
A. the default BGP route policy
B. global variables that can be referenced by any route policy
C. the global default route policy
D. hierarchical route policy
E. nested route policy
Correct Answer: B Section: (none) Explanation
Explanation/Reference:
Global Configuration Mode
Prompt: (config)
Enter global configuration mode from executive (EXEC) mode by using the configure command. Global configuration commands generally apply to the whole system rather than just one protocol or interface. You can enter all other configuration submodes listed in this section from global configuration mode.
RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)#
Global Parameter Configuration Mode
Prompt: (config-rpl-gl)
Enter global parameter configuration mode by using the policy-global command in global configuration mode. In global parameter configuration mode, you can create or modify a global policy by entering successive commands and then terminating the configuration by entering the end-global command.
For example, to configure global parameters:
RP/0/RP0/CPU0:router(config)# policy-global RP/0/RP0/CPU0:router(config-rp-gl)# glbpathtype ebgp RP/0/RP0/CPU0:router(config-rp-gl)# glbtag 100 RP/0/RP0/CPU0:router(config-rp-gl)# end-global
QUESTION 44
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.
Correct Answer: D Section: (none) Explanation
QUESTION 45
Refer to the Cisco IOS XR route policy exhibit. Which two statements are correct? (Choose two.)
A. “test” and “foo” are references to the community sets.
B. The “match-any” option indicates matching either the standard community or extended community.
C. Routes that match both the “test” and “foo” conditions will have their local preference set to 20.
D. All non-matching routes will be permitted.
Correct Answer: AD Section: (none) Explanation
Explanation/Reference:
“First Test, First Pass” – www.lead2pass.com 19 Cisco 642-883 Exam
QUESTION 46
When redistributing routes into OSPF, which kind of routes will be redistributed by default on Cisco IOS XR Software but will not be automatically redistributed by default on Cisco IOS Software and Cisco IOS XE Software?
A. Type 1 external routes
B. Type 2 external routes
C. subnetted routes
D. /32 host routes
E. tagged static routes
Correct Answer: C Section: (none) Explanation
QUESTION 47
When redistributing EIGRP routes into OSPF as type E2 external OSPF routes, what is the default OSPF seed metric?
A. Infinite
B. 0
C. 1
D. 10
E. 20
Correct Answer: E Section: (none) Explanation
QUESTION 48
Refer to the exhibit. Which Cisco IOS XR configuration is missing to complete the configuration task of enabling BFD with only the OSPF peer over the gi0/3/0/1 interface in area 0?
A. bfd fast-detect also needs to be enabled globally under router ospf 100. RP/0/RSP0/CPU0:P1(config-ospf)#bfd fast-detect
B. bfd fast-detect also needs to be enabled for the OSPF area under area 0. RP/0/RSP0/CPU0:P1(config-ospf-ar)#bfd fast-detect
C. bfd fast-detect also needs to be enabled for the OSPF interface under area 0 interface gi0/3/0/1. RP/0/RSP0/CPU0:P1(config-ospf-ar-if)#bfd fast-detect
D. bfd fast-detect also needs to be enabled globally on the router. RP/0/RSP0/CPU0:P1(config#bfd fast-detect
E. bfd fast-detect also needs to be enabled on the gi0/3/0/1 interface under interface gi0/3/0/1. RP/0/RSP0/CPU0:P1(config-if)#bfd fast-detect
Correct Answer: C Section: (none) Explanation
Explanation/Reference: bfd fast-detect
To enable Bidirectional Forwarding Detection (BFD) to detect failures in the path between adjacent forwarding engines, use the bfd fast-detect command in the appropriate configuration mode. To return the software to the default state in which BFD is not enabled, use the no form of this command.
bfd fast-detect [disable | ipv4]
no bfd fast-detect
QUESTION 49
Which high-availability routing feature requires the neighbor router to support the graceful restart capability?
A. BFD
B. NSR
C. NSF
D. MTR
Correct Answer: C Section: (none) Explanation
Explanation/Reference:
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
QUESTION 50
Which high-availability mechanism is a detection protocol that is enabled at the interface and at the routing protocol levels?
A. NSF
B. SSO
C. NSR
D. BFD
E. SDR
Correct Answer: D Section: (none) Explanation
Explanation/Reference:
http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/fs_bfd.html
QUESTION 51
Refer to the Cisco IOS show command output shown in the exhibit. Which of the following statements is correct?
A. The best path to 10.2.10.1/32 was chosen because of the AS path.
B. The best path to 10.2.10.1/32 was chosen because of the weight.
C. The best path to 10.2.10.1/32 was chosen because of the local preference.
D. The best path to 10.2.10.1/32 was chosen because of the MED.
E. The best path to 10.2.10.1/32 was chosen because of the route origin. “First Test, First Pass” – www.lead2pass.com 21 Cisco 642-883 Exam
Correct Answer: B Section: (none) Explanation
QUESTION 52
Which OSPF feature allows a router with redundant route processors to maintain its OSPF state and adjacencies across planned and unplanned RP switchovers and does this by checkpointing state information from OSPF on the active RP to the standby RP? This feature does not require the OSPF neighbor to support graceful restart.
A. NSR
B. NSF
C. BFD
D. MTR
E. SDR
Correct Answer: A Section: (none) Explanation
Explanation/Reference: Continuous Forwarding
An important aspect of high availability is maintenance of traffic forwarding, even in the case of control-plane switchovers. Cisco IOS XR Software has several built-in features that can provide continuous forwarding, including RSP stateful switchover (SSO), Nonstop Forwarding (NSF), Graceful Restart, and NSR.
●
NSF: Cisco IOS XR Software supports forwarding without traffic loss during a brief outage of the control plane through signaling and routing protocol implementations for Graceful Restart extensions as standardized by the IETF. In addition to standards compliance, this implementation has been compatibility tested with Cisco IOS Software and third-party operating systems.
●
Graceful Restart: This control-plane mechanism ensures high availability by allowing detection and recovery from failure conditions while preserving NSF services. Graceful Restart is a way to recover from signaling and control-plane failures without affecting the forwarding plane. Cisco IOS XR Software uses this feature and a combination of check pointing, mirroring, RSP redundancy, and other system resiliency features to recover prior to timeout and avoid service downtime as a result of network reconvergence.
●
NSR: This feature allows for the forwarding of data packets to continue along known routes while the routing protocol information is being refreshed following a processor switchover. NSR maintains protocol sessions and state information across SSO functions for services such as Multiprotocol Label Switching (MPLS) VPN. TCP connections and the routing protocol sessions are migrated from the active RSP to the standby RSP after the RSP failover without letting the peers know about the failover. The sessions terminate locally on the failed RSP, and the protocols running on the standby RSP reestablish the sessions after the standby RSP goes active, without the peer detecting the change. You can also use NSR with Graceful Restart to protect the routing control plane during switchovers. The Cisco IOS XR Operating System provides system resiliency through a comprehensive set of high-availability features including modularity, process restart, fault handling, continuous forwarding, and upgradability.
QUESTION 53
Which two statements regarding OSPFv2 or OSPFv3 authentication are correct? (Choose two.)
A. OSPFv2 supports MD5 authentication.
B. OSPFv2 supports MD5 or SHA authentication.
C. OSPFv2 relies on the native security stack that uses IPsec.
D. OSPFv3 supports MD5 authentication.
E. OSPFv3 supports MD5 or SHA authentication.
F. OSPFv3 relies on the native security stack that uses IPsec.
Correct Answer: AF Section: (none) Explanation
QUESTION 54
What are three common problems that can cause a BGP neighbor state to toggle between the idle state and the active state? (Choose three.)
A. BGP network command misconfiguration
B. route policy misconfiguration
C. AS number misconfiguration
D. route map misconfiguration
E. BGP neighbor peering to wrong IP address
F. IGP routing problem: not able to reach the source IP address of the BGP open packet
Correct Answer: CEF Section: (none) Explanation
QUESTION 55
BGP peerings can be secured using which protection mechanism?
A. SHA authentication
B. MD5 authentication
C. SSH
D. SSL “First Test, First Pass” – www.lead2pass.com 22 Cisco 642-883 Exam
E. AAA
F. digital certificates
Correct Answer: B Section: (none) Explanation
Explanation/Reference:
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a0080b52107.shtml
QUESTION 56
In an AS with 10 routers running IBGP, how many IBGP sessions will be required to establish fully meshed IBGP peerings?
A. 10
B. 20
C. 45
D. 50
E. 99
F. 100
Correct Answer: C Section: (none) Explanation
Explanation/Reference:
N * (N-1) /2
QUESTION 57
You are implementing OSPF as the IGP using a single OSPF area design. The router memory usage for OSPF is too high. Which two methods can lower the OSPF memory usage? (Choose two.)
A. enable OSPF synchronization
B. implement multi-area OSPF
C. enable OSPF sham links to reduce the number of LSAs
D. implement route summarization on the ABRs
E. enable route leaking between Level 1 and Level 2 areas
Correct Answer: BD Section: (none) Explanation
QUESTION 58
Routes that are received from an IBGP peer will be propagated to which other routers by default?
A. to the EBGP peers only
B. to the IBGP peers only
C. to both EBGP and IBGP peers
D. to no other peers
Correct Answer: A Section: (none) Explanation
QUESTION 59
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 “First Test, First Pass” – www.lead2pass.com 23 Cisco 642-883 Exam
E. routing loops may temporarily be introduced into the network
Correct Answer: BD Section: (none) Explanation
QUESTION 60
When monitoring the OSPF operations in the network, you notice that the OSPF process is not load balancing traffic across multiple OSPF links. Which configuration adjustment could be made to enable the OSPF process to load balance traffic across multiple OSPF links?
A. Enable BFD on the OSPF interfaces and on the OSPF routing process.
B. Enable NSR on the OSPF routing process.
C. Enable NSF on the OSPF routing process.
D. Adjust the OSPF cost on the OSPF interfaces.
E. Adjust the OSPF variance parameter.
F. Use the wide-style OSPF metric instead of the narrow-style OSPF metric.
Correct Answer: D Section: (none) Explanation
QUESTION 61
Refer to the network diagram in the exhibit. If both ASBRs are advertising the external Destination X network as OSPF E2 route, what is the best path for the R1 router to reach Network X?
A. R1 will use the path via ASBR 2 as the best path.
B. R1 will use the path via ASBR 1 as the best path.
C. R1 will load balance between two equal cost paths via ASBR 1 and ASBR 2.
D. R1 will sees two equal costs and will choose the path through the ASBR with the lower OSPF router ID.
Correct Answer: B Section: (none) Explanation
Explanation/Reference:
“First Test, First Pass” – www.lead2pass.com 24 Cisco 642-883 Exam
QUESTION 62
Refer to the show command output in the exhibit. For which reason will this router drop all traffic that is destined to the 1.1.1.0/24 network?
A. The 1.1.1.0/24 route is not synchronized.
B. The BGP next hop for reaching the 1.1.1.0/24 network is not reachable.
C. The metric of the 1.1.1.0/24 route is set to 0.
D. The weight of the 1.1.1.0/24 route is set to 0.
E. The 1.1.1.0/24 route is an incomplete route.
F. The IBGP split-horizon rule is preventing the router to use the IBGP route.
Correct Answer: B Section: (none) Explanation
QUESTION 63
Which of the following is used by an IS-IS router to detect other IS-IS neighbor routers and to form adjacencies?
A. ESH
B. ISH
C. IIH
D. PSNP
E. CSNP
Correct Answer: C Section: (none) Explanation
Explanation/Reference:
ISIS actually features three different hello types An ES Hello (ESH) is send by all End Systems, and all IS devices listen for this Hello An IS Hello (ISH) announces the presence of an IS – An IS Hello is sent by all IS devices, and End Systems listen for these hellos
Finally, an IS-to-IS Hello (IIH) is used by an IS to discover other ISes and to form adjacencies with them
A router will send an IIH to another router on the link to form or maintain an adjacency, but it will still send an ISH as well in case there are end systems located on that segment
QUESTION 64
Hotspot
“First Test, First Pass” – www.lead2pass.com 29 Cisco 642-883 Exam How many total OSPF virtual links are configured in this multiarea OSPF network which supports both OSPFv2 and OSPFv3 for IPv4 and IPv6 routing?
A. 1
B. 2 “First Test, First Pass” – www.lead2pass.com 30 Cisco 642-883 Exam
C. 3
D. 4
Correct Answer: B Section: (none) Explanation
Explanation/Reference:
#Show running-config | include virtual check how many router having “virtual ” entry
QUESTION 65
“First Test, First Pass” – www.lead2pass.com 31 Cisco 642-883 Exam
Which statement Is correct regarding the DR election process In this OSPF implementation?
A. Both the CE5 and PE6 routers are DROTHERs
B. PE5 is the OSPFv2 DR for the GigabitEthernet link between PE5 and PE6
C. PE6 is the OSPFv2 and OSPFv3 DR for the GigabitEthernet link between PE5 and PE6
D. PE6 is the DR for the GigabitEthernet link between PE5 and PE6 because it has a higher OSPF priority
Correct Answer: A Section: (none) Explanation
Explanation/Reference:
# show ip ospf neighbor # show ipv6 ospf neighbor
QUESTION 66
“First Test, First Pass” – www.lead2pass.com 32 Cisco 642-883 Exam On the PE5 router, there are how many IPv4 and IPv6 OSPF neighbors and how many IPv4 OSPF interfaces? (Choose three)
A. two ipv4 ospf neighbors
B. three ipv4 ospf neighbors “First Test, First Pass” – www.lead2pass.com 33 Cisco 642-883 Exam
C. two ipv6 ospf neighbors
D. three ipv6 ospf neighbors
E. three ipv4 ospf interfaces
F. four ipv4 ospf interfaces
Correct Answer: AEF Section: (none) Explanation
Explanation/Reference:
# show ip ospf neighbor # show ipv6 ospf neighbor
QUESTION 67
“First Test, First Pass” – www.lead2pass.com 34 Cisco 642-883 Exam
Which three statements are correct regarding the OSPF operations? line (Choose three.)
A. PE5 OSPFv2 and OSPFv3 router id is 10.5.1.1
B. The OSPF virtual-link cost is 1
C. Area 3 is a transit area
D. Area 4 is using MD5 authentication
E. Area 1 IPv4 and IPv6 networks are not reachable from PE6
Correct Answer: CDE Section: (none) Explanation
Explanation/Reference:
#show ip protocols #show ip route ospf #show ip ospf interfaces #show ip ospf neighbors #show ip ospf database #show ip ospf border-routers #show ip ospf #show ip route #show ip protocols
QUESTION 68
Hotspot
“First Test, First Pass” – www.lead2pass.com 35 Cisco 642-883 Exam What is the configured IS-IS circuit-type between the CE5 and PE5 routers and between the PE5 and PE6 routers? (Choose two.)
A. Circuittype L1 between CE5 and PE5 4
B. Circuittype L1/L2 between CE5 and PE5
C. Circuittype L2 between CE5 and PE5
D. Circuittype L1 between PE5 and PE6
E. Circuittype L1/L2 between PE5 and PE6
F. Circuittype L2 between PE5 and PE6
Correct Answer: AF Section: (none) Explanation
Explanation/Reference:
#show clns neighbor
“First Test, First Pass” – www.lead2pass.com 36 Cisco 642-883 Exam
QUESTION 69
Which router(s) is/are IS-Type L1/L2 IS-IS router?
A. CE5 only
B. PE6 only
C. CE5 and PE6 only
D. PE5 and PE6 only
E. CE5, PE5 and PE6
Correct Answer: D Section: (none)
Explanation Explanation/Reference:
“First Test, First Pass” – www.lead2pass.com 37 Cisco 642-883 Exam
#show clns neighbor
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