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

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Q1. Consider an OSPFv3 network with four parallel links between each pair of routers. Which measure can you use to reduce the CPU load and at the same time keep all links available for ECMP? 

A. Configure some interfaces as passive interface. 

B. Configure ipv6 ospf priority 0 on some interfaces. 

C. Configure some routers with a distribute list in ingress of the OSPFv3 process. 

D. Configure ipv6 ospf database-filter all out on some interfaces. 

Answer:

Explanation: 

To filter outgoing link-state advertisements (LSAs) to an Open Shortest Path First version 3 (OSPFv3) interface, use the ipv6 ospf database-filter all out command in interface configuration mode. This can be done on some of the links to reduce the CPU load while still ensuring that all links in the equal cost path are still being used. 

Q2. Which two statements about private VLANs are true? (Choose two.) 

A. Only one isolated VLAN can be mapped to a primary VLAN. 

B. Only one community VLAN can be mapped to a primary VLAN. 

C. Multiple isolated VLANs can be mapped to a primary VLAN. 

D. Multiple community VLANs can be mapped to a primary VLAN. 

Answer: A,D 

Explanation: 

An isolated VLAN is a secondary VLAN that carries unidirectional traffic upstream from the hosts toward the promiscuous ports. You can configure only one isolated VLAN in a PVLAN domain. An isolated VLAN can have several isolated ports. The traffic from each isolated port also remains completely separate. Only one isolated VLAN can be mapped under a given primary VLAN. A community VLAN is a secondary VLAN that carries upstream traffic from the community ports to the promiscuous port and to other host ports in the same community. You can configure multiple community VLANs in a PVLAN domain. The ports within one community can communicate, but these ports cannot communicate with ports in any other community or isolated VLAN in the private VLAN. 

Reference: http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus6000/sw/layer2/6x/b_6k_L ayer2_Config_6x/b_6k_Layer2_Config_602N12_chapter_011.html 

Q3. Refer to the exhibit. 

Which BGP feature allows R1 to instruct R2 which prefixes it is allowed to advertise to R1? 

A. route refresh 

B. Prefix-Based Outbound Route Filtering 

C. distribute lists 

D. prefix lists 

Answer:

Q4. Refer to the exhibit. 

R1, R2, and R3 have full network connectivity to each other, but R2 prefers the path through R3 to reach network 172.17.1.0/24. Which two actions can you take so that R2 prefers the path through R1 to reach 172.17.1.0/24? (Choose two.) 

A. Set the reference bandwidth to 10000 on R1, R2, and R3. 

B. Configure the cost on the link between R1 and R3 to be greater than 100 Mbps. 

C. Set the reference bandwidth on R2 only. 

D. Configure a manual bandwidth statement with a value of 1 Gbps on the link between R1 and R3. 

E. Modify the cost on the link between R1 and R2 to be greater than 10 Gbps. 

F. Configure a manual bandwidth statement with a value of 100 Mbps on the link between R1 and R2. 

Answer: A,B 

Explanation: 

By default, the reference bandwidth used in Cisco routers is 100Mbps, so FastEthernet and above will have a cost of 1, so a gigabit interface and 10GE interface will be equal with a fastethernet. This is not ideal. If we change the reference bandwidth to 100000 then the faster links will be used. Changing the reference bandwidth needs to be done on all routers in the OSPF network. Increasing the cost on the R1-R3 link will also cause the traffic to take the more direct route. 

Q5. Which statement about WAN Ethernet Services is true? 

A. Rate-limiting can be configured per EVC. 

B. Point-to-point processing and encapsulation are performed on the customer network. 

C. Ethernet multipoint services function as a multipoint-to-multipoint VLAN-based connection. 

D. UNIs can perform service multiplexing and all-in-one bundling. 

Answer:

Explanation: 

The MEF has defined a set of bandwidth profiles that can be applied at the UNI or to an EVC. A bandwidth profile is a limit on the rate at which Ethernet frames can traverse the UNI or the EVC. 

Reference: http://www.ciscopress.com/articles/article.asp?p=101367&seqNum=2 

Q6. Which technology facilitates dynamic tunnel establishment in DMVPN? 

A. CEF 

B. mGRE 

C. a dynamic routing protocol 

D. NHRP 

Answer:

Q7. Which two methods can you use to limit the range for EIGRP queries? (Choose two.) 

A. Use an access list to deny the multicast address 224.0.0.1 outbound from select EIGRP neighbor and permit everything else. 

B. Configure route tagging for all EIGRP routes. 

C. Summarize routes at the boundary routers of the EIGRP domain. 

D. Configure unicast EIGRP on all routers in the EIGRP domain. 

E. Configure stub routers in the EIGRP domain. 

F. Use an access list to deny the multicast address 224.0.0.10 outbound from select EIGRP neighbors and permit everything else. 

Answer: C,E 

Q8. Which option is the default maximum age of the MAC address table? 

A. 300 seconds 

B. 500 seconds 

C. 1200 seconds 

D. 3600 seconds 

Answer:

Explanation: 

To configure the maximum aging time for entries in the Layer 2 table, use the mac-address-table aging-time command in global configuration mode. 

Syntax Description 

seconds 

MAC address table entry maximum age. Valid values are 0, and from 5 to 1000000 seconds. Aging time is counted from the last time that the switch detected the MAC address. The default value is 300 seconds. 

Reference: http://www.cisco.com/c/en/us/td/docs/ios/lanswitch/command/reference/lsw_book/lsw_m1. html 

Q9. You are configuring a DHCPv6 client for a DHCPv6 server with the prefix delegation feature. Which option is a result of the interface configuration when you enter the command ipv6 address autoconfig default? 

A. a static IPv6 default route pointing to the upstream DHCP server 

B. a static IPv6 default route pointing to the upstream DHCP relay 

C. a static IPv6 default route pointing to the upstream router 

D. a temporary stateless address, formed from the EUI-64 bit address and the prefix from the route advertisement of the upstream router 

Answer:

Q10. Refer to the exhibit. 

Which device role could have generated this debug output? 

A. an NHS only 

B. an NHC only 

C. an NHS or an NHC 

D. a DMVPN hub router 

Answer:

Explanation: 

NHRP works off a server/client relationship, where the NHRP clients (let’s call them next hop clients/NHCs) register with their next hop server (NHS), it’s the responsibility of the NHS to track all of its NHCs this is done with registration request and reply packets. Here we see a registration request, which can only be sent by an NHC.