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

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Q1. Which two services are used to transport Layer 2 frames across a packet-switched network? (Choose two.) 

A. Frame Relay 

B. ATM 

C. AToM 

D. L2TPv3 

Answer: C,D 

Explanation: 

Both AToM and L2TPv3 have the common objective of transmitting packet switched traffic of L2 frames (Frame Relay, ATM, and Ethernet) across a packet-switched network. 

Reference: Layer 2 VPN Architectures - Google Books Result Wei Luo, Carlos Pignataro, Anthony Chan 

https://books.google.com/books?isbn=0132796864 

Q2. Which statement about the BGP scope of the cost community is true? 

A. It is shared with IBGP neighbors only. 

B. It is shared with IBGP neighbors and route reflectors. 

C. It is shared with EBGP neighbors only. 

D. It is shared with IBGP and EBGP neighbors. 

E. It is shared with IBGP and confederation peers. 

Answer:

Explanation: 

The BGP Cost Community feature introduces the cost extended community attribute. The cost community is a non-transitive extended community attribute that is passed to internal BGP (iBGP) and confederation peers but not to external BGP (eBGP) peers. The cost community feature allows you to customize the local route preference and influence the best path selection process by assigning cost values to specific routes. 

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

Q3. Refer to the exhibit. 

Which option is the result of this configuration? 

A. Devices in OSPF area 15 can reach the summary route 192.168.0.0/16 and its more specific subnets. 

B. Devices in OSPF area 15 can reach only the more specific routes of 192.168.0.0/16. 

C. Devices in OSPF area 0 can reach the summary route 192.168.0.0/16 and its more specific subnets. 

D. Devices in OSPF area 0 can reach only the summary route of 192.168.0.0/16. 

Answer:

Explanation: 

. area range 

To consolidate and summarize routes at an area boundary, use the area range command in router configuration mode. To disable this function, use theno form of this command. Area area-id range ip-address mask [advertise | not-advertise] [cost cost] no area area-id range ip-address mask [advertise | not-advertise] [cost cost] 

. Syntax Description 

area-id 

Identifier of the area about which routes are to be summarized. It can be specified as either a decimal value or as an IP address. 

ip-address 

IP address. 

mask 

IP address mask. 

advertise 

(Optional) Sets the address range status to advertise and generates a Type 3 summary link-state advertisement (LSA). 

not-advertise 

(Optional) Sets the address range status to DoNotAdvertise. The Type 3 summary LSA is suppressed, and the component networks remain hidden from other networks. 

Reference: http://www.cisco.com/c/en/us/td/docs/ios/12_2/iproute/command/reference/fiprrp_r/1rfospf. html 

Q4. Refer to the exhibit. 

A tunnel is configured between R3 to R4 sourced with their loopback interfaces. The ip pim sparse-dense mode command is configured on the tunnel interfaces and multicast-routing is enabled on R3 and R4. The IP backbone is not configured for multicast routing. 

The RPF check has failed toward the multicast source. 

Which two conditions could have caused the failure? (Choose two.) 

A. The route back to the RP is through a different interface than tunnel 0. 

B. The backbone devices can only route unicast traffic. 

C. The route back to the RP is through the same tunnel interface. 

D. A static route that points the RP to GigabitEthernet1/0 is configured. 

Answer: A,D 

Explanation: 

.For a successful RPF verification of multicast traffic flowing over the shared tree (*,G) from RP, an ip mroute rp-address nexthop command needs to be configured for the RP address, that points to the tunnel interface. 

A very similar scenario can be found at the reference link below: 

Reference: http://www.cisco.com/c/en/us/support/docs/ip/ip-multicast/43584-mcast-over-gre.html 

Q5. Which option is an incorrect design consideration when deploying OSPF areas? 

A. area 1 - area 0 - MPLS VPN backbone - area 0 - area 2 

B. area 1 - MPLS VPN backbone - area 2 

C. area 1 - MPLS VPN backbone - area 1 

D. area 2 - area 0 - MPLS VPN backbone - area 1 

E. area 0 - area 2 - MPLS VPN superbackbone - area 1 

Answer:

Explanation: 

In the case of MPLS-VPN Backbone as The OSPF superbackbone behaves exactly like Area 0 in regular OSPF, so we cannot have two different area 0’s that are not directly connected to each other. When area 0 connects to the superbackbone, it simply becomes an extension of area 0. 

Q6. Refer to the exhibit. 

Which two options are effects of the given configuration? (Choose two.) 

A. It sets the data export destination to 209.165.200.227 on UDP port 49152. 

B. It enables Cisco Express Forwarding on interface FastEthernet0/0. 

C. It configures the export process to include the BGP peer AS of the router gathering the data. 

D. It enables NetFlow switching on interface FastEthernet0/0. 

E. It sets the data export destination to 209.165.200.227 on TCP port 49152. 

Answer: A,D 

Explanation: 

The “ip flow-export destination 209.165.200.227 49152” command specifies that the data export destination server is 209.165.200.227 using UDP port 49152. 

The “ip route-cache flow” command under the fastethernet 0/0 interface enable netflow switching on that interface. 

Q7. Which two statements about proxy ARP are true? (Choose two.) 

A. It is supported on networks without ARP. 

B. It allows machines to spoof packets. 

C. It must be used on a network with the host on a different subnet. 

D. It requires larger ARP tables. 

E. It reduces the amount of ARP traffic. 

Answer: B,D 

Explanation: 

Disadvantages of Proxy ARP 

Hosts have no idea of the physical details of their network and assume it to be a flat network in which they can reach any destination simply by sending an ARP request. But using ARP for everything has disadvantages. These are some of the disadvantages: 

It increases the amount of ARP traffic on your segment. 

Hosts need larger ARP tables in order to handle IP-to-MAC address mappings. 

Security can be undermined. A machine can claim to be another in order to intercept packets, an act called "spoofing." 

It does not work for networks that do not use ARP for address resolution. 

It does not generalize to all network topologies. For example, more than one router that connects two physical networks. 

Reference: http://www.cisco.com/c/en/us/support/docs/ip/dynamic-address-allocation-resolution/13718-5.html 

Q8. Which statement is true about conditional advertisements? 

A. Conditional advertisements create routes when a predefined condition is met. 

B. Conditional advertisements create routes when a predefined condition is not met. 

C. Conditional advertisements delete routes when a predefined condition is met. 

D. Conditional advertisements create routes and withhold them until a predefined condition is met. 

E. Conditional advertisements do not create routes, they only withhold them until a predefined condition is met. 

Answer:

Explanation: 

The Border Gateway Protocol (BGP) conditional advertisement feature provides additional control of route advertisement, depending on the existence of other prefixes in the BGP table. Normally, routes are propagated regardless of the existence of a different path. The BGP conditional advertisement feature uses the non-exist-map and the advertise-map keywords of the neighbor advertise-map command in order to track routes by the route prefix. If a route prefix is not present in output of the non-exist-map command, then the route specified by the advertise-map command is announced. This feature is useful for multihomed networks, in which some prefixes are advertised to one of the providers only if information from the other provider is not present (this indicates a failure in the peering session or partial reachability). 

Reference: http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/16137-cond-adv.html 

Q9. Refer to the exhibit. 

What is the PHB class on this flow? 

A. EF 

B. none 

C. AF21 

D. CS4 

Answer:

Explanation: 

This command shows the TOS value in hex, which is 80 in this case. The following chart shows some common DSCP/PHB Class values: 

Service 

DSCP value 

TOS value 

Juniper Alias 

TOS hexadecimal 

DSCP - TOS Binary 

Premium IP 

46 

184 

ef 

B8 

101110 - 101110xx 

LBE 

32 

cs1 

20 

001000 - 001000xx 

DWS 

32 

128 

cs4 

80 

100000 - 100000xx 

Network control 

48 

192 

cs6 

c0 

110000 - 110000xx 

Network control 2 

56 

224 

cs7 

e0 

111000 - 111000xx 

Reference: http://www.tucny.com/Home/dscp-tos 

Q10. DRAG DROP 

Drag and drop the argument of the ip cef load-sharing algorithm command on the left to the function it performs on the right. 

Answer: