Cause all that matters here is passing the Cisco 642-883 exam. Cause all that you need is a high score of 642-883 Deploying Cisco Service Provider Network Routing (SPROUTE) exam. The only one thing you need to do is downloading Testking 642-883 exam study guides now. We will not let you down with our money-back guarantee.

2021 Oct 642-883 exam question

Q21. 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. 

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. 

Answer: C 


Q22. Which two features are specific only to Tier 3 providers? (Choose two.) 

A. interconnects with Tier Level 1 and Tier Level 2 ISPs in public peering points 

B. only purchases transit from other networks to reach the Internet 

C. purchases transit and pays settlements to other service providers 

D. uses strict route filtering to allow only customer and local routes to be sent to upstream providers 

E. receives a full Internet routing table via BGP from its upstream provider, which it can use for load-balancing traffic 

Answer: B,D 


Q23. When configuring BGP on Cisco IOS XR Software, which address-family is enabled by default? 

A. IPv4 unicast 

B. IPv6 unicast 

C. VPNv4 

D. IPv4 unicast and IPv6 unicast 

E. IPv4 unicast and IPv6 unicast and VPNv4 

F. No address-family is enabled by default. 

Answer: F 

Explanation: 

http://www.cisco.com/en/US/docs/ios_xr_sw/iosxr_r3.8/routing/command/reference/rr38bg p.pdf 

An address family must be explicitly configured in the router configuration mode for the address family to be active in BGP. Similarly, an address family must be configured under the neighbor for the BGP session to be established for that address family. An address family must be configured in router configuration mode before it can be configured under a neighbor. 


Q24. 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. 


Q25. Which two mandatory tasks must an IS-IS NSF-capable router perform for RP switchover? (Choose two.) 

A. Relearn the available IS-IS neighbors. 

B. Reacquire the contents of the LSD. 

C. Reset peering with the available IS-IS neighbors. 

D. Keep the existing contents of the LSD. 

E. Rediscover DIS for each link segment. 

Answer: A,B 


Updated 642-883 latest exam:

Q26. What is recursive lookup in BGP and how does it work? 

A. The router looks up the EBGP route and the EBGP next hop to reach a destination in the remote AS. Then the router looks up the route to reach the EBGP next hop using the IBGP. 

B. The router looks up the IBGP route and the IBGP next hop to reach a destination in the remote AS. Then the router looks up the route to reach the IBGP next hop using the EBGP. 

C. The router looks up the BGP route and the BGP next hop to reach a destination in the remote AS. Then the router looks up the route to reach the BGP next hop using the IGP. 

D. The router looks up the route and the next hop to reach a destination in the remote AS using the IGP. Then the router looks up the route to reach the next hop using BGP. 

E. The router perform three routing lookups to determine the route to reach a destination in the remote AS. The first lookup is done using EBGP, the second lookup is done using IBGP, and the third lookup is done using the IGP. 

Answer: C 

Explanation: 

A few different approaches are available to deal with iBGP and synchronization. We may turn on the synchronization option on our routers and wait for the IGP to have a route for the destination before it’s advertised to peers. Another option is to simply use a full mesh, so that iBGP convergence isn’t an issue. Clearly that isn’t going to happen when a network’s core needs to scale: it will implement something like reflectors that cause iBGP’s full mesh to be broken. The real alternative, if you don’t enable synchronization, is to use route recursion. A recursive route lookup uses the BGP next-hop attribute to actually make a different route lookup. The IGP can use the destination network instead of the AS-path to determine where it gets sent. Even if the iBGP hasn’t converged, the routers will still know how to get to that network, since it will exist in the router it was advertised from, who will know the next-hop. 


Q27. 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 


Q28. Which configuration implements the most secured OSPF authentication mode on Cisco IOS XE? 

A. interface Gi0/0/0/0 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco 

B. router ospf 1 area 1 authentication message-digest interface GigabitEthernet0/0/0/0 message-digest-key 1 md5 cisco 

C. router ospf 1 area 1 interface GigabitEthernet0/0/0/0 authentication message-digest message-digest-key 1 md5 cisco 

D. router ospf 1 area 1 authentication interface GigabitEthernet0/0/0/0.ip ospf authentication-key cisco 

E. interface Gi0/0/0/0 ip ospf authentication ip ospf authentication-key cisco 

Answer: A 


Q29. 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 


Q30. 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