Ensurepass

 

QUESTION 51

DRAG DROP

Drag and drop the Cisco IOS XE subpackage on the left to the function it performs on the right.

 

clip_image001

 

Correct Answer:

clip_image002

 

 

 

 

 

 

 

 

 

QUESTION 52

Refer to the exhibit. If you change the Spanning Tree Protocol from pvst to rapid-pvst, what is the effect on the interface Fa0/1 port state?

 

clip_image004

 

A.

It transitions to the listening state, and then the forwarding state.

B.

It transitions to the learning state and then the forwarding state.

C.

It transitions to the blocking state, then the learning state, and then the forwarding state.

D.

It transitions to the blocking state and then the forwarding state.

 

Correct Answer: C

Explanation:

First, the port will transition to the blocking state, immediately upon the change, then it will transition to the new RSTP states of learning and forwarding.

Port States

There are only three port states left in RSTP that correspond to the three possible operational states. The 802.1D disabled, blocking, and listening states are merged into a unique 802.1w discarding state.

STP (802.1D) Port State

RSTP (802.1w) Port State

Is Port Included in Active Topology?

Is Port Learning MAC Addresses?

Disabled

Discarding

No

No

Blocking

Discarding

No

No

Listening

Discarding

Yes

No

Learning

Learning

Yes

Yes

Forwarding

Forwarding

Yes

Yes

 

 

QUESTION 53

Which type of port would have root guard enabled on it?

 

A.

A root port

B.

An alternate port

C.

A blocked port

D.

A designated port

 

Correct Answer: D

Explanation:

The root guard feature provides a way to enforce the root bridge placement in the network. The root gu
ard ensures that the port on which root guard is enabled is the designated port. Normally, root bridge ports are all designated ports, unless two or more ports of the root bridge are connected together. If the bridge receives superior STP Bridge Protocol Data Units (BPDUs) on a root guard-enabled port, root guard moves this port to a root-inconsistent STP state. This root- inconsistent state is effectively equal to a listening state. No traffic is forwarded across this port. In this way, the root guard enforces the position of the root bridge.

Reference: http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/10588-74.html

 

 

QUESTION 54

Refer to the exhibit. While troubleshooting high CPU utilization on one of your Cisco Catalyst switches, you find that the issue is due to excessive flooding that is caused by STP. What can you do to prevent this issue from happening again?

 

clip_image006

 

A.

Disable STP completely on the switch.

B.

Change the STP version to RSTP.

C.

Configure PortFast on port-channel 1.

D.

Configure UplinkFast on the switch.

E.

Configure PortFast on interface Gi0/15.

 

Correct Answer: E

Explanation:

Topology Changes (TC) should be a rare event in a well-configured network. When a link on a switch port goes up or down, there is eventually a TC, once the STP state of the port is changing to or from forwarding. When the port is flapping, this would cause repetitive TCs and flooding. Ports with the STP portfast feature enabled will not cause TCs when going to or from the forwarding state. The configuration of portfast on all end-device ports (such as printers, PCs, and servers) should limit TCs to a low amount and is highly recommended.

Reference: http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/28943-170.html

 

 

QUESTION 55

Refer to the exhibit. All switches have default bridge priorities, and originate BPDUs with MAC addresses as indicated. The numbers shown are STP link metrics. Which two ports are forwarding traffic after STP converges? (Choose two.)

 

clip_image008

 

A.

The port connecting switch SWD with switch SWE

B.

The port connecting switch SWG with switch SWF

C.

The port connecting switch SWC with switch SWE

D.

The port connecting switch SWB with switch SWC

Correct Answer: CD

Explanation:

Here, we know SWB to SWC are forwarding because we already identified the blocking port. So for the last correct answer let’s consider what must be done to prevent a switch loop between SWC/SWD/SWE. SWE to SWD will be blocked because SWC has a lower MAC address so it wins the forwarding port. And to look at it further, you could try to further understand what would happen with ports on SWG. Would the ports on SWG try to go through SWE or SWF? SWE has the lower MAC address so the port from SWG to SWE would win the forwarding election.

Therefore, answer B could never be correct.

 

 

QUESTION 56

Refer to the exhibit. Which three statements about the output are true? (Choose three.)

 

clip_image010

 

A.

An mrouter port can be learned by receiving a PIM hello packet from a multicast router.

B.

This switch is configured as a multicast router.

C.

Gi2/0/1 is a trunk link that connects to a multicast router.

D.

An mrouter port is learned when a multicast data stream is received on that port from a multicast router.

E.

This switch is not configured as a multicast router. It is configured only for IGMP snooping.

F.

IGMP reports are received only on Gi2/0/1
and are never transmitted out Gi2/0/1 for VLANs 10 and 20.

 

Correct Answer: ABC

Explanation:

In this example, the switch has been configured as a multicast router since IGMP snooping has been enabled. All mrouters can learn about other mrouters by receiving a PIM hello packet from another multicast router. Also, since two different VLANs are being used by the same port of gi 2/0/1, it must be a trunk link that connects to another multicast router.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

QUESTION 57

Refer to the exhibit. If a port is configured as shown and receives an untagged frame, of which VLAN will the untagged frame be a member?

 

clip_image012

 

A.

VLAN 1

B.

VLAN 2

C.

VLAN 3

D.

VLAN 4

 

Correct Answer: B

Explanation:

When typing:

Switch(config-if)#switchport mode ?

access Set trunking mode to ACCESS unconditionally

dynamic Set trunking mode to dynamically negotiate access or trunk mode trunk Set trunking mode to TRUNK unconditionally

and

Switch(config-if)#switchport mode dynamic ?

auto Set trunking mode dynamic negotiation parameter to AUTO

desirable Set trunking mode dynamic negotiation parameter to DESIRABLE So if we configure Fa0/1 as dynamic auto mode, it will not initiate any negotitation but waiting for the other end negotiate to be a trunk with DTP. If the other end does not ask it to become a trunk then it will become an access port. Therefore when using the “show interface fastEthernet0/1 switchport” command we will see two output lines “Administrative Mode. dynamic auto” and “Operational Mode. static access”

Note. To set this port to VLAN 2 as the output above just use one additional command.

switchport access vlan 2.

Now back to our question, from the output we see that Fa0/1 is operating as an access port on VLAN 2 so if it receive untagged frame it will suppose that frame is coming from VLAN 2.

 

 

QUESTION 58

Refer to the exhibit. Which statement describes the effect on the network if FastEthernet0/1 goes down temporarily?

 

clip_image014

 

A.

FastEthernet0/2 forwards traffic only until FastEthernet0/1 comes back up.

B.

FastEthernet0/2 stops forwarding traffic until FastEthernet0/1 comes back up.

C.

FastEthernet0/2 forwards traffic indefinitely.

D.

FastEthernet0/1 goes into standby.

 

Correct Answer: C

Explanation:

Use the switchport backup interface interface configuration command on a Layer 2 interface to configure Flex Links, a pair of interfaces that provide backup to each other. Use the no form of this command to remove the Flex Links configuration.

With Flex Links configured, one link acts as the primary interface and forwards traffic, while the other interface is in standby mode, ready to begin forwarding traffic if the primary link shuts down. The interface being configured is referred to as the active link; the specified interface is identified as the backup link. The feature provides an alternative to the Spanning Tree Protocol (STP), allowing users to turn off STP and still retain basic link redundancy.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/12-2_53_se/command/reference/2960ComRef/cli3.html#wp3269214

 

 

 

 

 

 

 

 

 

 

 

QUESTION 59

Refer to the exhibit. Which technology does the use of bi-directional BPDUs on all ports in the topology support?

 

clip_image016

 

A.

RSTP

B.

MST

C.

Bridge Assurance

D.

Loop Guard

E.

Root Guard

F.

UDLD

 

Correct Answer: C

Explanation:

Spanning Tree Bridge Assurance

 

clip_image018

 

Bridge Assurance (BA) can help protect against bridging loops where a port becomesdesignated because it has stopped receiving BPDUs. This is similar to the functionof loop guard.

Reference: http://lostintransit.se/tag/convergence/

 

 

 

 

 

 

QUESTION 60

Which three statements are true about PPP CHAP authentication? (Choose three.)

 

A.

PPP encapsulation must be enabled globally.

B.

The LCP phase must be complete and in closed state.

C.

The hostname used by a router for CHAP authentication cannot be changed.

D.

PPP encapsulation must be enabled on the interface.

E.

The LCP phase must be complete
and in open state.

F.

By default, the router uses its hostname to identify itself to the peer.

 

Correct Answer: DEF

Explanation:

Point-to-Point Protocol (PPP) authentication issues are one of the most common causes for dialup link failures. This document provides some troubleshooting procedures for PPP authentication issues.

Prerequisites

Note. By default, the router uses its hostname to identify itself to the peer. However, this CHAP username can be changed through the ppp chap hostname command.

Reference: http://www.cisco.com/c/en/us/support/docs/wan/point-to-point-protocol-ppp/25647-understanding-ppp-chap.html

 

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