400-101 Exam - CCIE Routing and Switching (v5.0)

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Q1. In IPv6 Path MTU Discovery, which ICMP message is sent by an intermediary router that requires a smaller MTU? 

A. Time Exceeded, with code 1 (fragment reassembly time exceeded) 

B. Packet Too Big 

C. Destination Unreachable, with code 4 (the datagram is too big) 

D. Multicast Termination Router 

Answer:

Q2. Which option describes how a VTPv3 device responds when it detects a VTPv2 device on a trunk port? 

A. It sends VTPv3 packets only. 

B. It sends VTPv2 packets only. 

C. It sends VTPv3 and VTPv2 packets. 

D. It sends a special packet that contains VTPv3 and VTPv2 packet information. 

Answer:

Explanation: 

When a VTP version 3 device on a trunk port receives messages from a VTP version 2 device, the VTP version 3 device sends a scaled-down version of the VLAN database on that particular trunk in a VTP version 2 format. A VTP version 3 device does not send out VTP version 2-formatted packets on a trunk port unless it first receives VTP version 2 packets on that trunk. If the VTP version 3 device does not receive VTP version 2 packets for an interval of time on the trunk port, the VTP version 3 device stops transmitting VTP version 2 packets on that trunk port. Even when a VTP version 3 device detects a VTP version 2 device on a trunk port, the VTP version 3 device continues to send VTP version 3 packets in addition to VTP version 3 device 2 packets, to allow two kinds of neighbors to coexist on the trunk. VTP version 3 sends VTP version 3 and VTP version 2 updates on VTP version 2-detected trunks. 

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/vtp.html 

Q3. What is the purpose of EIGRP summary leaking? 

A. to allow a summary to be advertised conditionally on specific criteria 

B. to allow a component of a summary to be advertised in addition to the summary 

C. to allow overlapping summaries to exist on a single interface 

D. to modify the metric of the summary based on which components of the summary are operational 

Answer:

Explanation: 

When you do manual summarization, and still you want to advertise some specific routes to the neighbor, you can do that using leak-map. Please read more about leaking routes here. 

http://www.cisco.com/c/en/us/td/docs/ios/iproute_eigrp/command/reference/ire_book/ire_i1. html#wp1037685. 

Q4. When you migrate a network from PVST+ to rapid-PVST+, which two features become inactive? (Choose two.) 

A. Root guard 

B. Loop guard 

C. UplinkFast 

D. UDLD 

E. BackboneFast 

F. Bridge Assurance 

Answer: C,E 

Explanation: 

It is good to know the UplinkFast and BackboneFast behavior before you start the migration process. 

Here, the Access1 switch runs Cisco IOS. This output is taken before migration to the rapid-PVST+ mode: 

Access1#show spanning-tree vlan 10 

VLAN0010 

Spanning tree enabled protocol ieee 

Root ID Priority 24586 

Address 0015.63f6.b700 

Cost 3019 

Port 107 (FastEthernet3/0/1) 

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec 

Bridge ID Priority 49162 (priority 49152 sys-id-ext 10) 

Address 000f.f794.3d00 

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec 

Aging Time 300 

Uplinkfast enabled 

Interface Role Sts Cost Prio.Nbr Type 

Fa3/0/1 Root FWD 3019 128.107 P2p 

Fa3/0/2 Altn BLK 3019 128.108 P2p 

Access1#show spanning-tree summary 

Switch is in pvst mode 

Root bridge for: none 

Extended system ID is enabled 

Portfast Default is disabled 

PortFast BPDU Guard Default is enabled 

Portfast BPDU Filter Default is disabled 

Loopguard Default is disabled 

EtherChannel misconfig guard is enabled 

UplinkFast is enabled 

BackboneFast is enabled 

Configured Pathcost method used is short 

Name Blocking Listening Learning Forwarding STP Active 

VLAN0010 1 0 0 1 2 

VLAN0020 1 0 0 1 2 

2 vlans 2 0 0 2 4 

This output is taken after the mode is changed to rapid-PVST+: 

Access1#show spanning-tree vlan 10 

VLAN0010 

Spanning tree enabled protocol rstp 

Root ID Priority 24586 

Address 0015.63f6.b700 

Cost 3019 

Port 107 (FastEthernet3/0/1) 

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec 

Bridge ID Priority 49162 (priority 49152 sys-id-ext 10) 

Address 000f.f794.3d00 

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec 

Aging Time 300 

UplinkFast enabled but inactive in rapid-pvst mode 

Interface Role Sts Cost Prio.Nbr Type 

Fa3/0/1 Root FWD 3019 128.107 P2p 

Fa3/0/2 Altn BLK 3019 128.108 P2p 

Access1#show spanning-tree summary 

Switch is in rapid-pvst mode 

Root bridge for: none 

Extended system ID is enabled 

Portfast Default is disabled 

PortFast BPDU Guard Default is enabled 

Portfast BPDU Filter Default is disabled 

Loopguard Default is disabled 

EtherChannel misconfig guard is enabled 

UplinkFast is enabled but inactive in rapid-pvst mode 

BackboneFast is enabled but inactive in rapid-pvst mode 

Configured Pathcost method used is short 

Name Blocking Listening Learning Forwarding STP Active 

VLAN0010 1 0 0 1 2 

VLAN0020 1 0 0 1 2 

2 vlans 2 0 0 2 4 

You can see in the show spanning-tree summary command output that UplinkFast and BackboneFast are enabled, but are inactive in rapid-PVST mode. 

Reference: http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6500-series-switches/72836-rapidpvst-mig-config.html#upback1 

Q5. Refer to the exhibit. 

The customer wants to use IP SLA to create a failover to ISP2 when both Ethernet connections to ISP1 are down. The customer also requires that both connections to ISP1 are utilized during normal operations. 

Which IP route configuration accomplishes these requirements for the customer? 

A. ip route 0.0.0.0 0.0.0.0 192.168.0.1 track 1 

ip route 0.0.0.0 0.0.0.0 192.168.1.1 track 2 

ip route 0.0.0.0 0.0.0.0 192.168.2.1 track 3 

B. ip route 0.0.0.0 0.0.0.0 192.168.0.1 track 1 

ip route 0.0.0.0 0.0.0.0 192.168.1.1 track 2 

ip route 0.0.0.0 0.0.0.0 192.168.2.1 track 4.100 

C. ip route 0.0.0.0 0.0.0.0 192.168.0.1 track 1 

ip route 0.0.0.0 0.0.0.0 192.168.1.1 track 2 

ip route 0.0.0.0 0.0.0.0 192.168.2.1 track 3.100 

D. ip route 0.0.0.0 0.0.0.0 192.168.0.1 track 1 1 

ip route 0.0.0.0 0.0.0.0 192.168.1.1 track 2 2 

ip route 0.0.0.0 0.0.0.0 192.168.2.1 track 3 3 

Answer:

Q6. Which two statements are true about unicast RPF? (Choose two.) 

A. Unicast RPF requires CEF to be enabled. 

B. Unicast RPF strict mode works better with multihomed networks. 

C. Unicast RPF strict mode supports symmetric paths. 

D. Unicast RPF strict mode supports asymmetric paths. 

E. CEF is optional with Unicast RPF, but when CEF is enabled it provides better performance. 

Answer: A,C 

Explanation: 

Unicast RPF requires Cisco express forwarding (CEF) to function properly on the router. 

Strict Versus Loose Checking Mode 

The Unicast RPF in Strict Mode feature filters ingress IPv4 traffic in strict checking mode and forwards packets only if the following conditions are satisfied. 

. An IPv4 packet must be received at an interface with the best return path (route) to the packet source (a process called symmetric routing). There must be a route in the Forwarding Information Base (FIB) that matches the route to the receiving interface. Adding a route in the FIB can be done via static route, network statement, or dynamic routing. 

. IPv4 source addresses at the receiving interface must match the routing entry for the interface. 

References: 

http://www.cisco.com/c/en/us/td/docs/ios/12_2/security/configuration/guide/fsecur_c/scfrpf. html 

http://www.cisco.com/c/en/us/td/docs/ios/12_0s/feature/guide/srpf_gsr.html 

Q7. Which statement describes Cisco PfR link groups? 

A. Link groups enable Cisco PfR Fast Reroute when NetFlow is enabled on the external interfaces of the border routers. 

B. Link groups define a strict or loose hop-by-hop path pReference: 

C. Link groups are required only when Cisco PfR is configured to load-balance all traffic. 

D. Link groups are enabled automatically when Cisco PfR is in Fast Reroute mode. 

E. Link groups set a preference for primary and fallback (backup) external exit interfaces. 

Answer:

Explanation: 

The Performance Routing - Link Groups feature introduced the ability to define a group of exit links as a preferred set of links, or a fallback set of links for PfR to use when optimizing traffic classes specified in an PfR policy. PfR currently selects the best link for a traffic class based on the preferences specified in a policy and the traffic class performance—using parameters such as reachability, delay, loss, jitter or MOS—on a path out of the specified link. 

Reference: http://www.cisco.com/c/en/us/td/docs/ios/pfr/configuration/guide/15_1/pfr_15_1_book/pfr-link-group.html 

Q8. Refer to the exhibit. 

Which statement about this IP SLA is true? 

A. The SLA must also have a schedule configured before it will start. 

B. The TTL of the SLA packets is 10. 

C. The SLA has a timeout of 3.6 seconds. 

D. The SLA has a lifetime of 5 seconds. 

Answer:

Explanation: 

When you configure an IP SLAs operation, you must schedule the operation to begin capturing statistics and collecting error information. You can schedule an operation to start immediately or to start at a certain month, day, and hour. You can use the pending option to set the operation to start at a later time. The pending option is an internal state of the operation that is visible through SNMP. The pending state is also used when an operation is a reaction (threshold) operation waiting to be triggered. You can schedule a single IP SLAs operation or a group of operations at one time. We can see in this output that the IP SLA is still in a pending trigger state. 

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/12-2/44sg/configuration/guide/Wrapper-44SG/swipsla.html 

Q9. What are the three primary components of NetFlow? (Choose three.) 

A. Flow caching 

B. A flow collector 

C. The data analyzer 

D. Flow sequence numbers 

E. Cisco Express Forwarding 

F. Multicast 

Answer: A,B,C 

Explanation: 

NetFlow includes three key components that perform the following capabilities: 

. Flow caching analyzes and collects IP data flows entering router or switch interfaces and prepares data for export. It enables the accumulation of data on flows with unique characteristics, such as IP addresses, application, and CoS. 

. FlowCollector and Data Analysis captures exported data from multiple routers and filters and aggregates the data according to customer policies, and then stores this summarized or aggregated data. Users can leverage Cisco NetFlow collector as a flow collector, or they can opt for a variety of third-party partner products. A Graphical user interface displays and analyzes NetFlow data collected from FlowCollector files. This allows users to complete near-real-time visualization or trending analysis of recorded and aggregated flow data. Users can specify the router and aggregation scheme and desired time interval. 

Reference: http://www.cisco.com/c/en/us/products/collateral/ios-nx-os-software/ios-netflow/product_data_sheet0900aecd80173f71.html 

Q10. Refer to the exhibit. 

Assuming that the peer is configured correctly and the interface is up, how many neighbors will be seen in the EIGRPv6 neighbor table on this IPv6-only router? 

A. one neighbor, which will use a local router-id of 6010. AB8. . /64 

B. one neighbor, which will use a local router-id of 6020. AB8. . /64 

C. none, because EIGRPv6 only supports authenticated peers 

D. none, because of the mismatch of timers 

E. none, because there is no EIGRP router ID configured 

Answer:

Explanation: 

Configuring EIGRP for IPv6 has some restrictions; they are listed below: 

. The interfaces can be directly configured with EIGRP for IPv6, without the use of a global IPv6 address. There is no network statement in EIGRP for IPv6. 

. The router ID needs to be configured for an EIGRPv6 protocol instance before it can run. 

. EIGRP for IPv6 has a shutdown feature. Ensure that the routing process is in "no shut" mode to start running the protocol. 

Reference: http://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/113267-eigrp-ipv6-00.html