Free Sharing CertBus Updated Cisco 400-101 VCE and PDF Exam Practice Materials

CertBus 2018 Latest Cisco 400-101 CCIE Exam VCE and PDF Dumps for Free Download!

400-101 CCIE Exam PDF and VCE Dumps : 1063QAs Instant Download: [100% 400-101 Exam Pass Guaranteed or Money Refund!!]
☆ Free view online pdf on CertBus free test 400-101 PDF:
☆ CertBus 2018 Latest 400-101 CCIE exam Question PDF Free Download from Google Drive Share:

Following 400-101 1063QAs are all new published by Cisco Official Exam Center

100% candidates have passed the CCIE May 18,2018 Hotest 400-101 vce dumps exam by the help of CertBus pass guaranteed CCIE Hotest 400-101 practice preparation materials. The CertBus Cisco PDF and VCEs are the latest and cover every knowledge points of CCIE Latest 400-101 exam questions CCIE Routing and Switching Written v5.0 certifications. You can try the Q and As for an undeniable success in Newest 400-101 QAs exam.

CertBus exam guide: pass the 400-101 exam on your first attempt! 400-101 exam guide and practice test – CertBus exam achiever. CertBus 400-101 certification dumps : oracle, ibm and many more. CertBus 400-101 online study guides. pass 400-101 exam | 400-101 written test | 400-101 exam study guide | 400-101 exam tips. CertBus 400-101 dumps free download.

We CertBus has our own expert team. They selected and published the latest 400-101 preparation materials from Cisco Official Exam-Center:


Refer to the exhibit.

R1 has an EBGP session to ISP 1 and an EBGP session to ISP 2. R1 receives the same prefixes

through both links.

Which configuration should be applied so that the link between R1 and ISP 2 will be preferred for

outgoing traffic (R1 to ISP 2)?

A. Increase local preference on R1 for received routes

B. Decrease local preference on R1 for received routes

C. Increase MED on ISP 2 for received routes

D. Decrease MED on ISP 2 for received routes

Answer: A

Explanation: Explanation

Local preference is an indication to the AS about which path has preference to exit the AS in order

to reach a certain network. A path with higher local preference is preferred more. The default value

of preference is 100.





Refer to the exhibit.

A small enterprise connects its office to two ISPs, using separate T1 links. A static route is used

for the default route, pointing to both interfaces with a different administrative distance, so that one

of the default routes is preferred.

Recently the primary link has been upgraded to a new 10 Mb/s Ethernet link.

After a few weeks, they experienced a failure. The link did not pass traffic, but the primary static

route remained active. They lost their Internet connectivity, even though the backup link was


Which two possible solutions can be implemented to avoid this situation in the future? (Choose


A. Implement HSRP link tracking on the branch router R1.

B. Use a track object with an IP SLA probe for the static route on R1.

C. Track the link state of the Ethernet link using a track object on R1.

D. Use a routing protocol between R1 and the upstream ISP.

Answer: B,D


Interface Tracking

Interface tracking allows you to specify another interface on the router for the HSRP process to

monitor in order to alter the HSRP priority for a given group.

If the specified interface\’s line protocol goes down, the HSRP priority of this router is reduced,

allowing another HSRP router with higher priority can become active (if it has preemption


To configure HSRP interface tracking, use the standby [group] track interface [priority] command.

When multiple tracked interfaces are down, the priority is reduced by a cumulative amount. If you

explicitly set the decrement value, then the value is decreased by that amount if that interface is

down, and decrements are cumulative. If you do not set an explicit decrement value, then the

value is decreased by 10 for each interface that goes down, and decrements are cumulative.

The following example uses the following configuration, with the default decrement value of 10.

Note: When an HSRP group number is not specified, the default group number is group 0.

interface ethernet0

ip address

standby ip

standby priority 110

standby track serial0

standby track serial1

The HSRP behavior with this configuration is:

0 interfaces down = no decrease (priority is 110)

1 interface down = decrease by 10 (priority becomes100)

2 interfaces down = decrease by 10 (priority becomes 90)




Which statement is true about TCN propagation?

A. The originator of the TCN immediately floods this information through the network.

B. The TCN propagation is a two step process.

C. A TCN is generated and sent to the root bridge.

D. The root bridge must flood this information throughout the network.

Answer: C



New Topology Change Mechanisms

When an 802.1D bridge detects a topology change, it uses a reliable mechanism to first notify the

root bridge.

This is shown in this diagram:

Once the root bridge is aware of a change in the topology of the network, it sets the TC flag on the

BPDUs it sends out, which are then relayed to all the bridges in the network. When a bridge

receives a BPDU with the TC flag bit set, it reduces its bridging-table aging time to forward delay

seconds. This ensures a relatively quick flush of stale information. Refer to Understanding

Spanning-Tree Protocol Topology Changes for more information on this process. This topology

change mechanism is deeply remodeled in RSTP. Both the detection of a topology change and its

propagation through the network evolve.

Topology Change Detection

In RSTP, only non-edge ports that move to the forwarding state cause a topology change. This

means that a loss of connectivity is not considered as a topology change any more, contrary to

802.1D (that is, a port that moves to blocking no longer generates a TC). When a RSTP bridge

detects a topology change, these occur:

It starts the TC While timer with a value equal to twice the hello-time for all its non-edge

designated ports and its root port, if necessary.

It flushes the MAC addresses associated with all these ports.

Note: As long as the TC While timer runs on a port, the BPDUs sent out of that port have the TC

bit set.

BPDUs are also sent on the root port while the timer is active.

Topology Change Propagation

When a bridge receives a BPDU with the TC bit set from a neighbor, these occur:

It clears the MAC addresses learned on all its ports, except the one that receives the topology


It starts the TC While timer and sends BPDUs with TC set on all its designated ports and root port

(RSTP no longer uses the specific TCN BPDU, unless a legacy bridge needs to be notified).

This way, the TCN floods very quickly across the whole network. The TC propagation is now a one

step process. In fact, the initiator of the topology change floods this information throughout the

network, as opposed to 802.1D where only the root did. This mechanism is much faster than the

802.1D equivalent. There is no need to wait for the root bridge to be notified and then maintain the

topology change state for the whole network for seconds.

In just a few seconds, or a small multiple of hello-times, most of the entries in the CAM tables of

the entire network (VLAN) flush. This approach results in potentially more temporary flooding, but

on the other hand it clears potential stale information that prevents rapid connectivity restitution.



Which statement is true about loop guard?

A. Loop guard only operates on interfaces that are considered point-to-point by the spanning tree.

B. Loop guard only operates on root ports.

C. Loop guard only operates on designated ports.

D. Loop guard only operates on edge ports.

Answer: A



Understanding How Loop Guard Works

Unidirectional link failures may cause a root port or alternate port to become designated as root if

BPDUs are absent. Some software failures may introduce temporary loops in the network. Loop

guard checks if a root port or an alternate root port receives BPDUs. If the port is receiving

BPDUs, loop guard puts the port into an inconsistent state until it starts receiving BPDUs again.

Loop guard isolates the failure and lets spanning tree converge to a stable topology without the

failed link or bridge.

You can enable loop guard per port with the set spantree guard loop command.

Note When you are in MST mode, you can set all the ports on a switch with the set spantree

global-defaults loop-guard command.

When you enable loop guard, it is automatically applied to all of the active instances or VLANs to

which that port belongs. When you disable loop guard, it is disabled for the specified ports.

Disabling loop guard moves all loop-inconsistent ports to the listening state.

If you enable loop guard on a channel and the first link becomes unidirectional, loop guard blocks

the entire channel until the affected port is removed from the channel. Figure 8-6 shows loop

guard in a triangle switch configuration.

Figure 8-6 Triangle Switch Configuration with Loop Guard

Figure 8-6 illustrates the following configuration:

Switches A and B are distribution switches.

Switch C is an access switch.

Loop guard is enabled on ports 3/1 and 3/2 on Switches A, B, and C.

Use loop guard only in topologies where there are blocked ports. Topologies that have no blocked

ports, which are loop free, do not need to enable this feature. Enabling loop guard on a root switch

has no effect but provides protection when a root switch becomes a nonroot switch.

Follow these guidelines when using loop guard:

Do not enable loop guard on PortFast-enabled or dynamic VLAN ports.

Do not enable PortFast on loop guard-enabled ports.

Do not enable loop guard if root guard is enabled.

Do not enable loop guard on ports that are connected to a shared link.

Note: We recommend that you enable loop guard on root ports and alternate root ports on access


Loop guard interacts with other features as follows:

Loop guard does not affect the functionality of UplinkFast or BackboneFast.

Root guard forces a port to always be designated as the root port. Loop guard is effective only if

the port is a root port or an alternate port. Do not enable loop guard and root guard on a port at the

same time.

PortFast transitions a port into a forwarding state immediately when a link is established. Because

a PortFast-enabled port will not be a root port or alternate port, loop guard and PortFast cannot be

configured on the same port. Assigning dynamic VLAN membership for the port requires that the

port is PortFast enabled. Do not configure a loop guard-enabled port with dynamic VLAN


If your network has a type-inconsistent port or a PVID-inconsistent port, all BPDUs are dropped

until the misconfiguration is corrected. The port transitions out of the inconsistent state after the

message age expires. Loop guard ignores the message age expiration on type-inconsistent ports

and PVID-inconsistent ports. If the port is already blocked by loop guard, misconfigured BPDUs

that are received on the port make loop guard recover, but the port is moved into the type-

inconsistent state or PVID-inconsistent state.

In high-availability switch configurations, if a port is put into the blocked state by loop guard, it

remains blocked even after a switchover to the redundant supervisor engine. The newly activated

supervisor engine recovers the port only after receiving a BPDU on that port.

Loop guard uses the ports known to spanning tree. Loop guard can take advantage of logical ports

provided by the Port Aggregation Protocol (PAgP). However, to form a channel, all the physical

ports grouped in the channel must have compatible configurations. PAgP enforces uniform

configurations of root guard or loop guard on all the physical ports to form a channel.

These caveats apply to loop guard:


Which two are effects of connecting a network segment that is running 802.1D to a network

segment that is running 802.1w? (Choose two.)

A. The entire network switches to 802.1D and generates BPDUs to determine root bridge status. B.

A migration delay of three seconds occurs when the port that is connected to the 802.1D bridge

comes up.

C. The entire network reconverges and a unique root bridge for the 802.1D segment, and a root

bridge for the 802.1w segment, is chosen.

D. The first hop 802.1w switch that is connected to the 802.1D runs entirely in 802.1D compatibility

mode and converts the BPDUs to either 802.1D or 802.1w BPDUs to the 802.1D or 802.1w

segments of the network.

E. Classic 802.1D timers, such as forward delay and max-age, will only be used as a backup, and

will not be necessary if point-to-point links and edge ports are properly identified and set by the


Answer: B,E


Each port maintains a variable that defines the protocol to run on the corresponding segment. A

migration delay timer of three seconds also starts when the port comes up. When this timer runs,

the current STP or RSTP mode associated to the port is locked. As soon as the migration delay

expires, the port adapts to the mode that corresponds to the next BPDU it receives. If the port

changes its mode of operation as a result of a BPDU received, the migration delay restarts.

802.1D works by the concept that the protocol had to wait for the network to converge before it

transitioned a port into the forwarding state. With Rapid Spanning Tree it does not have to rely on

any timers, the only variables that that it relies on is edge ports and link types.

Any uplink port that has an alternate port to the root can be directly placed into the forwarding

state (This is the Rapid convergence that you speak of “restored quickly when RSTP is already in

use?”). This is what happened when you disconnected the primary look; the port that was ALT,

moved to FWD immediately, but the switch also still needs to create a BDU with the TC bit set to

notify the rest of the network that a topology has occurred and all non-edge designated ports will

transition to BLK, LRN, and then FWD to ensure there are no loops in the rest of the network. This

is why if you have a host on a switchport, and you know for a fact that it is only one host, enable

portfast to configure the port as an edgeport so that it does not have to transition to all the STP



400-101 Practice Test400-101 Study Guide400-101 Braindumps


Which two statements are true about traffic shaping? (Choose two.)

A. Out-of-profile packets are queued.

B. It causes TCP retransmits.

C. Marking/remarking is not supported.

D. It does not respond to BECN and ForeSight Messages.

E. It uses a single/two-bucket mechanism for metering.

Answer: A,C



Which three options are features of VTP version 3? (Choose three.)

A. VTPv3 supports 8K VLANs.

B. VTPv3 supports private VLAN mapping.

C. VTPv3 allows for domain discovery.

D. VTPv3 uses a primary server concept to avoid configuration revision issues.

E. VTPv3 is not compatible with VTPv1 or VTPv2.

F. VTPv3 has a hidden password option.

Answer: B,D,F


Key Benefits of VTP Version 3

Much work has gone into improving the usability of VTP version 3 in three major areas:

The new version of VTP offers better administrative control over which device is allowed to update

other devices\’ view of the VLAN topology. The chance of unintended and disruptive changes is

significantly reduced, and availability is increased. The reduced risk of unintended changes will

ease the change process and help speed deployment.

Functionality for the VLAN environment has been significantly expanded. Two enhancements are

most beneficial for today\’s networks:


Refer to the exhibit.

Which statement is correct about the prefix

A. The prefix has encountered a routing loop.

B. The prefix is an aggregate with an as-set.

C. The prefix has been aggregated twice, once in AS 100 and once in AS 200.

D. None of these statements is true.

Answer: B



Refer to the exhibit.

What is the potential issue with this configuration?

A. There is no potential issue; OSPF will work fine in any condition.

B. Sub-optimal routing may occur since there is no area 1 adjacency between the ABRs.

C. This is a wrong OSPF configuration because all routers must be in area 0 only.

D. This is a wrong OSPF configuration because /30 requires wild card.

Answer: B



Refer to the exhibit.

Which path is selected as best path?

A. path 1, because it is learned from IGP B.

path 1, because the metric is the lowest C.

path 2, because it is external

D. path 2, because it has the higher router ID

Answer: B


CertBus exam braindumps are pass guaranteed. We guarantee your pass for the 400-101 exam successfully with our Cisco materials. CertBus CCIE Routing and Switching Written v5.0 exam PDF and VCE are the latest and most accurate. We have the best Cisco in our team to make sure CertBus CCIE Routing and Switching Written v5.0 exam questions and answers are the most valid. CertBus exam CCIE Routing and Switching Written v5.0 exam dumps will help you to be the Cisco specialist, clear your 400-101 exam and get the final success.

400-101 Latest questions and answers on Google Drive(100% Free Download):

400-101 Cisco exam dumps (100% Pass Guaranteed) from CertBus: [100% Exam Pass Guaranteed]

Why select/choose CertBus?

Millions of interested professionals can touch the destination of success in exams by products which would be available, affordable, updated and of really best quality to overcome the difficulties of any course outlines. Questions and Answers material is updated in highly outclass manner on regular basis and material is released periodically and is available in testing centers with whom we are maintaining our relationship to get latest material.

Brand Certbus Testking Pass4sure Actualtests Others
Price $45.99 $124.99 $125.99 $189 $69.99-99.99
Up-to-Date Dumps
Free 365 Days Update
Real Questions
Printable PDF
Test Engine
One Time Purchase
Instant Download
Unlimited Install
100% Pass Guarantee
100% Money Back
Secure Payment
Privacy Protection

Author: CertBus