Exam Code: 642-883 (Practice Exam Latest Test Questions VCE PDF)
Exam Name: Deploying Cisco Service Provider Network Routing (SPROUTE)
Certification Provider: Cisco
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Q1. RAG DROP
Answer:
Q2. Refer to the exhibit.
R1 is advertising subnets 1.1.1.X/32 via eBGP. XR4.must accept only the first seven subnets in its BGP table. Which configuration must occur on XR2 to meet these parameters?
A. route-policy INBOUND if destination in SUBNETS then pass endif router bgp 100 neighbor 10.10.14.1 address-family ipv4 unicast route-policy INBOUND in
B. route-policy INBOUND.if destination in FILTER then pass endif router bgp 100 neighbor 10.10.14.1 address-family ipv4 unicast route-policy INBOUND in
C. router bgp 100 neighbor 10.10.14.1 address-family ipv4 unicast route-policy FILTER in
D. router bgp 100 neighbor 10.10.14.1 address-family ipv4 unicast route-policy SUBNETS in
Answer: B
Q3. Which four statements are correct regarding IS-IS operations? (Choose four.)
A. By default, Level 1 routers within an IS-IS area do not carry any routing information external to the area to which they belong. They use a default route to exit the area.
B. Summarization should be configured on the Level 2 routers, which injects the Level 2 routes into Level 1.
C. IS-IS supports "route leaking" in which selected Level 2 routes can be advertised by a Level 1/Level 2 router into Level 1.
D. The IS-IS backbone is a contiguous collection of Level 1 capable routers, each of which can be in a different area.
E. With IS-IS, an individual router is in only one area, and the border between areas is on the link that connects two routers that are in different areas.
F. Cisco IOS XR Software supports multitopology for IPv6 IS-IS unless single topology is explicitly configured in IPv6 address-family configuration mode.
Answer: A,C,E,F
Explanation:
http://www.cisco.com/en/US/docs/ios_xr_sw/iosxr_r3.0/routing/configuration/guide/rc3isis.h tml#wp1148617
Single-Topology IPv6 Support
Single-topology IPv6 support on Cisco IOS XR software allows IS-IS for IPv6 to be configured on interfaces along with an IPv4 network protocol. All interfaces must be configured with the identical set of network protocols and all routers in the IS-IS area (for Level 1 routing) or the domain (for Level 2 routing) must support the identical set of network layer protocols on all interfaces.
When single-topology support for IPv6 is used, only narrow link metrics, also known as old-style type, length, value (TLV) arguments, may be employed. During single-topology operation, one shortest path first (SPF) computation per level is used to compute both IPv4 and IPv6 routes. Using a single SPF is possible because both IPv4 IS-IS and IPv6 IS-IS routing protocols share a common link topology. Because multitopology is the default behavior in the software, you must explicitly configure IPv6 to use the same topology as IPv4 in order to enable single-topology IPv6. Configure the single-topology command in ipv6 address family configuration submode of the IS-IS router stanza.
Multitopology IPv6 Support
Multitopology IPv6 support on Cisco IOS XR software differs from Cisco IOS software in that IS-IS assumes that multitopology support is required as soon as it detects interfaces configured for both IPv6 and IPv4 within the IS-IS stanza. You must use the metric-style wide command to configure IS-IS to wide link metrics as multitopology link advertisements.
Q4. 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
C. Two ipv6 ospf neighbors
D. Three ipv6 ospf neighbors
E. Three ipv4 ospf interfaces
F. Four ipv4 ospf interfaces
Answer: A,E,F
Explanation: # show ip ospf neighbor # show ipv6 ospf neighbor
Q5. 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
Answer: C
Explanation:
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
Q6. 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
C. 3
D. 4
Answer: B
Explanation:
#Show running-config | include virtual – check how many router having “virtual “ entry
Q7. Which two methods implement high availability in OSPF on Cisco IOS XR? (Choose two.)
A. NSF
B. NSR
C. BFD
D. fast hellos
E. sham-links
Answer: A,B
Q8. Which two statements about a transit AS are correct? (Choose two.)
A. A transit AS has eBGP connection(s) to only one external AS.
B. Routes between ASs are always exchanged via eBGP.
C. A transit AS uses an IGP like OSPF or ISIS to propagate the external networks within the transit AS.
D. Core routers within a transit AS normally use default routing to reach the external networks.
E. iBGP sessions can be established between non directly connected routers.
Answer: B,E
Q9. 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
Answer: A
Explanation:
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.
Q10. 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: B,D