640-878 Building Cisco Service Provider Next-Generation Networks, Part 2

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Question 1

Which Cisco router platform supports running either the Cisco IOS or IOS XR operating

  • A. Cisco CRS
  • B. Cisco ASR9k
  • C. Cisco ASR1K
  • D. Cisco ISR-G2
  • E. Cisco 12000 GSR

Answer : E

Explanation: Explanation/Reference: The CRS-1 platform natively runs the IOS XR operating system. The c12000 platform, originally being an IOS router, can be upgraded to run IOS XR. However, c12000 hardware, including line cards (LC) as well as route processors (RP), must be checked for XR compliance. TURBOBOOT refers to a fresh boot of the router from ROMMON. TURBOBOOT is required if an IOS router is being converted to IOS XR or as a last resort disaster recovery in the case of CRS-1. If the router is already running an IOS XR image, there is no need to TURBOBOOT the router for an upgrade or downgrade. Later sections in this chapter address the upgrade scenario. This section deals with a fresh boot of the router from ROMMON. A new c12000 platform can be ordered prebaked as an IOS XR router; however, there will always be cases where an IOS running c12000 needs to install IOS XR.

Question 2

During the BGP route selection process on Cisco routers, which BGP attribute is examined
first, to determine the best path to use?

  • A. AS path
  • B. MED
  • C. local preference
  • D. weight
  • E. origin

Answer : D

Question 3

Which four statements about REP configurations on a Cisco ME 3400 switch port are true?
(Choose four.)

  • A. The port must be an NNI type and must be in trunk mode.
  • B. Use the rep segment number command to enable REP on the switch port.
  • C. A REP segment cannot be wrapped into a ring topology. REP supports only a topology where each REP segment has two exit points via two edge switches.
  • D. The port where the segment terminates is called the edge port.
  • E. With REP, at least one port is always blocked in any given segment-that is, the alternate port.
  • F. If a failure occurs within the segment, the blocked port goes to the forwarding state after it goes through the listening state and the learning state.

Answer : A,B,D,E

Explanation: Explanation/Reference: http://www.cisco.com/en/US/docs/switches/metro/me3400/software/release/12.2_40_se/co nfiguration/guide/swrep.html Resilient Ethernet Protocol (REP) on the Cisco ME 3400E Ethernet Access switch. REP is a Cisco proprietary protocol that provides an alternative to Spanning Tree Protocol (STP) to control network loops, handle link failures, and improve convergence time. REP controls a group of ports connected in a segment, ensures that the segment does not create any bridging loops, and responds to link failures within the segment. REP provides a basis for constructing more complex networks and supports VLAN load balancing. REP Configuration Guidelines Follow these guidelines when configuring REP: We recommend that you begin by configuring one port and then configure the contiguous ports to minimize the number of segments and the number of blocked ports. If more than two ports in a segment fail when no external neighbors are configured, one port goes into a forwarding state for the data path to help maintain connectivity during configuration. In the show rep interface privileged EXEC command output, the Port Role for this port shows as Fail Logical Open; the Port Role for the other failed port shows as Fail No Ext Neighbor. When the external neighbors for the failed ports are configured, the ports go through the alternate port state transitions and eventually go to an open state or remain as the alternate port, based on the alternate port election mechanism. REP ports must be Layer 2 trunk ports. Be careful when configuring REP through a Telnet connection. Because REP blocks all VLANs until another REP interface sends a message to unblock it, you might lose connectivity to the switch if you enable REP in a Telnet session that accesses the switch through the same interface. You cannot run REP and STP or REP and Flex Links on the same segment or interface. If you connect an STP network to the REP segment, be sure that the connection is

Question 4

On Cisco IOS XR software, how is LDP enabled on an interface?

  • A. LDP is automatically enabled globally on all interfaces, when ip cef is enabled globally.
  • B. LDP is enabled on each interface, using the mpls ip interface configuration command.
  • C. LDP is enabled on each interface, using the interface command under mpls ldp (MPLS LDP configuration mode).
  • D. LDP is enabled globally on all interfaces, using the mpls ldp global configuration command.
  • E. LDP is enabled globally on all interfaces, using the mpls ip global configuration command.

Answer : C

Explanation: Explanation/Reference: http://www.cisco.com/en/US/docs/ios-xml/ios/mp_ldp/configuration/12-4m/mp-ldp-12-4m- book.pdf

Question 5

You have installed a new router and configured OSPF on it. However, this new router is not
able to establish an OSPF neighbor relationship with the neighbor OSPF router. Which four
conditions could cause this problem? (Choose four.)

  • A. mismatched OSPF hello/dead interval between the new router and the neighbor router
  • B. mismatched OSPF area ID between the new router and the neighbor router
  • C. mismatched OSPF authentication data between the new router and the neighbor router
  • D. mismatched OSPF router ID between the new router and the neighbor router
  • E. mismatched interface MTU between the new router and the neighbor router
  • F. mismatched interface bandwidth between the new router and the neighbor router

Answer : A,B,C,E

Question 6

A network administrator is troubleshooting an issue whereupon they able to ping the web
server, but unable to web browse to the same web server. When the administrator telnets
to the webserver on port 80, the administrator gets a connection refused message. At
which three layers of the OSI model does the problem exist? (Choose three.)

  • A. Layer 1
  • B. Layer 2
  • C. Layer 3
  • D. Layer 4
  • E. Layer 5
  • F. Layer 6
  • G. Layer 7

Answer : D,E,G

Question 7

What are two legitimate IPv4 to IPv6 migration technologies? (Choose two.)

  • A. Lift and shift
  • B. Dual stack backbones
  • C. In IPv4 / Out IPv6
  • D. IPv6 over IPv4 tunneling
  • E. IPv6 phasing

Answer : B,D

Question 8

Answer :

Question 9

You are enabling OSPF on a router and notice that all the Fast Ethernet and the Gigabit
Ethernet interfaces have the same OSPF cost of 1. Which single configuration change can
you make in router ospf configuration mode so that the Fast Ethernet interfaces have a
higher OSPF cost than the Gigabit Ethernet interfaces?

  • A. Change the OSPF interface cost globally.
  • B. Change the OSPF default metric.
  • C. Change the OSPF auto-cost reference bandwidth.
  • D. Change the OSPF administrative distance.
  • E. Change the OSPF metric type from E2 to E1.

Answer : C

Explanation: Explanation/Reference: http://ccietobe.blogspot.com/2008/06/ospf-auto-cost-reference-bandwidth_02.html

Question 10

Answer :

Question 11

Which three statements about access control lists on a Cisco IOS router are true? (Choose

  • A. The more specific ACL entries should be placed at the top of the ACL.
  • B. The generic ACL entries should be placed at the top of the ACL, to filter general traffic and reduce noise on the network.
  • C. ACLs always search for the most specific entry before taking any filtering action.
  • D. Router-generated packets cannot be filtered by the interface ACLs on the router.
  • E. Extended ACLs should be placed as close to the destination as possible.
  • F. There must be at least one permit statement in an ACL, or all traffic is denied.

Answer : A,D,F

Question 12

Refer to the partial Cisco IOS-XR configuration. What is the purpose of the for PFX to
PEER command?
mpls ldp
for PFX to PEER
!<output omitted>

  • A. To selectively enable LDP peering(s) with specific neighbors
  • B. To selectively disable LDP peering(s) with specific neighbors
  • C. To perform outbound filtering for local label advertisement for one or more prefixes to one or more peers
  • D. To perform inbound filtering for local label advertisement for one or more prefixes from one or more peers

Answer : C

Question 13

What layer of the IP NGN Model does the Customer Element and the Carrier Ethernet

  • A. Service Layer
  • B. Network Layer
  • C. Application Layer
  • D. Operational Layer

Answer : B

Question 14

Refer to the exhibit.
Which three commands are required on interface fastethernet 5/6 in order to create a trunk
link between another Cisco Catalyst Switch? (Choose three.)

  • A. no shutdown
  • B. switchport mode trunk
  • C. encapsulation trunk
  • D. switchport trunk encapsulation dot1Q
  • E. switchport trunk enable
  • F. no switchport
  • G. interface fastethernet 5/6 trunk
  • H. switchport trunk allow dot1Q

Answer : A,B,D

Question 15

Which two protocols are most often deployed in Cisco IP NGN multiservices core networks
to support services like VPNs? (Choose two.)

  • A. MPLS
  • B. GRE
  • C. mGRE
  • D. SSL
  • E. VTI
  • F. multiprotocol BGP

Answer : A,F

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