Ensurepass

CCIE Routing and Switching Written Exam v5.1

 

QUESTION 521

Which option describes the effect of the OSPF default-information originate always command?

 

A.

It creates a stub area.

B.

It configures the device to advertise a default route regardless of whether it exists in the routing table.

C.

It configures the device to automatically redistribute a default route.

D.

It adds a static default route to the device configuration.

 

Correct Answer: B

Explanation:

default-information originate

To generate a default external route into an Open Shortest Path First (OSPF) routing domain, use the default-information originate command in
router configuration mode. To disable this feature, use the no form of this command.

default-information originate [always] metric metric-value [ metric-type type-value ] [ route- map map-name ]

Syntax Description

always

(Optional) Always advertises the default route regardless of whether the software has a default route.

Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6/command/ipv6-cr-book/ipv6-d2.html

 

 

QUESTION 522

Which two statements about IS-IS are true? (Choose two.)

 

A.

The default hello interval is 10 seconds and the default hold timer is 30 seconds.

B.

The hello interval can be changed on a per-interface basis with the command isis hello-multiplier.

C.

Both routers need to have the same hello intervals and hold timers in order to form IS-IS neighbors.

D.

Both IS-IS routers need to have the same capabilities in the hello packet in order to form neighbors.

 

Correct Answer: AB

Explanation:

isis hello-interval

To specify the length of time between hello packets that the Cisco IOS software sends, use the isis hello-interval command in interface configuration mode. By default, a value three times the hello interval seconds is advertised as the hold time in the hello packets sent. (Change the multiplier of 3 by specifying the isis hello-multiplier command.) With smaller hello intervals, topological changes are detected faster, but there is more routing traffic.

The default is 10 seconds.

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

 

 

QUESTION 523

Which two options are the two underlying protocols on which a DMVPN relies? (Choose two.)

 

A.

IPsec

B.

NHRP

C.

GDOI

D.

ISAKMP

E.

SSL

F.

NLRI

 

Correct Answer: AB

 

 

QUESTION 524

You are implementing new addressing with EIGRP routing and must use secondary addresses, which are missing from the routing table. Which action is the most efficient solution to the problem?

 

A.

Disable split-horizon on the interfaces with secondary addresses.

B.

Disable split-horizon inside the EIGRP process on the router with the secondary interface addresses.

C.

Add additional router interfaces and move the secondary addresses to the new interfaces.

D.

Use a different routing protocol and redistribute the routes between EIGRP and the new protocol.

 

Correct Answer: A

Explanation:

Normally, routers that are connected to broadcast-type IP networks and that use distance-vector routing protocols employ the split horizon mechanism to reduce the possibility of routing loops. Split horizon blocks information about routes from being advertised by a router out of any interface from which that information originated. This behavior usually optimizes communications among multiple routers, particularly when links are broken. However, with nonbroadcast networks, situations can arise for which this behavior is less than ideal. For these situations, you might want to disable split horizon with EIGRP and RIP.

If an interface is configured with secondary IP addresses and split horizon is enabled, updates might not be sourced by every secondary address. One routing update is sourced per network number unless split horizon is disabled.

Reference: http://www.cisco.com/c/en/us/td/docs/ios/12_2/ip/configuration/guide/fipr_c/1cfrip.html

 

 

QUESTION 525

Which three statements about EIGRP and BFD are true? (Choose three.)

 

A.

BFD is independent of the routing protocol, so it can be used as a generic failure detection mechanism for EIGRP.

B.

Some parts of BFD can be distributed to the data plane, so it can be less CPU-intensive than reduced timers, which exist wholly at the control plane.

C.

Reduced EIGRP timers have an absolute minimum detection timer of 1-2 seconds; BFD can provide sub-second failure detection.

D.

BFD is tied to specific routing protocols and can be used for generic fault detection for the OSPF, EIGRP, and BGP routing protocols.

E.

BFD is dependent on the EIGRP routing protocol, so it can be used as a specific failure detection mechanism.

F.

BFD re
sides on the control plane, so it is less CPU-intensive than if it resided on the data plane.

 

Correct Answer: ABC

Explanation:

There are several advantages to implementing BFD over reduced timer mechanisms for routing protocols:

 

clip_image002Although reducing the EIGRP, IS-IS, and OSPF timers can result in minimum detection timer of one to two seconds, BFD can provide failure detection in less than one second.

clip_image002[1]Because BFD is not tied to any particular routing protocol, it can be used as a generic and consistent failure detection mechanism for EIGRP, IS-IS, and OSPF.

clip_image002[2]Because some parts of BFD can be distributed to the data plane, it can be less CPU-intensive than the reduced EIGRP, IS-IS, and OSPF timers, which exist wholly at the control plane.

 

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

 

 

QUESTION 526

Which three options are three benefits of an MPLS VPN? (Choose three.)

 

A.

It allows IP address space overlap by maintaining customer routes in a private routing table.

B.

It offers additional security by preventing intrusions directly into the customer routing table.

C.

It offers a transparent virtual network in which all customer sites appear on one LAN.

D.

It offers additional security by allowing only dynamic routing protocols between CE and PE routers.

E.

It allows IP address space overlap by maintaining customer routes in the global routing table with unique BGP communities.

F.

Providers can send only a default route for Internet access into the customer VPN.

 

Correct Answer: ABC

 

 

 

QUESTION 527

Which command drops packets with unknown source addresses until you remove a sufficient number of secure MAC addresses to drop below the maximum value, and also causes the Security Violation counter to increment?

 

A.

switchport port-security violation protect

B.

switchport port-security violation drop

C.

switchport port-security violation shutdown

D.

switchport port-security violation restrict

 

Correct Answer: D

Explanation:

When configuring port security violation modes, note the following information:

 

clip_image002[3]protect–Drops packets with unknown source addresses until you remove a sufficient number of secure MAC addresses to drop below the maximum value.

clip_image002[4]restrict–Drops packets with unknown source addresses until you remove a sufficient number of secure MAC addresses to drop below the maximum value and causes the SecurityViolation counter to increment.

clip_image002[5]shutdown–Puts the interface into the error-disabled state immediately and sends an SNMP trap notification.

 

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

 

 

QUESTION 528

Which two statements about BPDU guard are true? (Choose two.)

 

A.

The global configuration command spanning-tree portfast bpduguard default shuts down interfaces that are in the PortFast-operational state when a BPDU is received on that port.

B.

The interface configuration command spanning-tree portfast bpduguard enable shuts down only interfaces with PortFast enabled when a BPDU is received.

C.

BPDU guard can be used to prevent an access port from participating in the spanning tree in the service provider environment.

D.

BPDU guard can be used to protect the root port.

E.

BPDU guard can be used to prevent an invalid BPDU from propagating throughout the network.

 

Correct Answer: BC

 

 

QUESTION 529

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.

 

Correct Answer: E

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

 

 

QUESTION 530

DRAG DROP

Drag and drop the Metro Ethernet circuit on the left to the corresponding Service Type category on the right.

 

clip_image004

 

Correct Answer:

clip_image006

 

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