[Free] 2017(Oct) Dumps4cert Testinsides Cisco 200-125 Dumps with VCE and PDF Download 61-70

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CCNA Cisco Certified Network Associate CCNA (v3.0)

Question No: 61 – (Topic 2)

Refer to the exhibit.

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A network administrator is configuring an EtherChannel between SW1 and SW2. The SW1

configuration is shown. What is the correct configuration for SW2?

  1. interface FastEthernet 0/1 channel-group 1 mode active switchport trunk encapsulation dot1q switchport mode trunk

    interface FastEthernet 0/2 channel-group 1 mode active

    switchport trunk encapsulation dot1q switchport mode trunk

  2. interface FastEthernet 0/1 channel-group 2 mode auto switchport trunk encapsulation dot1q switchport mode trunk

    interface FastEthernet 0/2 channel-group 2 mode auto

    switchport trunk encapsulation dot1q switchport mode trunk

  3. interface FastEthernet 0/1 channel-group 1 mode desirable switchport trunk encapsulation dot1q switchport mode trunk

    interface FastEthernet 0/2 channel-group 1 mode desirable

    switchport trunk encapsulation dot1q switchport mode trunk

  4. interface FastEthernet 0/1 channel-group 1 mode passive switchport trunk encapsulation dot1q switchport mode trunk

interface FastEthernet 0/2 channel-group 1 mode passive

switchport trunk encapsulation dot1q switchport mode trunk

Answer: C Explanation:

If the etherchannel was configured with mode “auto”, it was using PagP, so, we need to configure the other switch with “desirable” mode.

PagP modes: auto | Desirable LACP modes: active | pasive

Question No: 62 – (Topic 2)

What are the possible trunking modes for a switch port? (Choose three.)

  1. transparent

  2. auto

  3. on

  4. desirable

  5. client

  6. forwarding

Answer: B,C,D Explanation:

These are the different types of trunk modes:

->ON: This mode puts the port into permanent trunk mode and negotiates to convert the link into a trunk link. The port becomes a trunk port even if the adjacent port does not agree to the change.

->OFF: This mode puts the port into permanent non-trunk mode and negotiates to convert the link into a non-trunk link. The port becomes a non-trunk port even if the adjacent port does not agree to the change.

->Desirable: This mode causes the port to actively attempt to convert the link into a trunk link. The port becomes a trunk port if the adjacent port is set to on, desirable, or auto mode.

->Auto: This mode enables the port to convert the link into a trunk link. The port becomes a trunk port if the adjacent port is set to on or desirable mode. This is the default mode for Fast and Gigabit Ethernet ports.

->Nonegotiate: This mode puts the port into permanent trunk mode, but does not allow the port to generate Dynamic Trunking Protocol (DTP) frames. The adjacent port must be configured manually as a trunk port to establish a trunk link.

Question No: 63 – (Topic 2)

What does a Layer 2 switch use to decide where to forward a received frame?

  1. source MAC address

  2. source IP address

  3. source switch port

  4. destination IP address

  5. destination port address

  6. destination MAC address

Answer: F Explanation:

When a frame is received, the switch looks at the destination hardware address and finds the interface if it is in its MAC address table. If the address is unknown, the frame is broadcast on all interfaces except the one it was received on.

Question No: 64 – (Topic 2)

Based on the network shown in the graphic

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Which option contains both the potential networking problem and the protocol or setting that should be used to prevent the problem?

  1. routing loops, hold down timers

  2. switching loops, split horizon

  3. routing loops, split horizon

  4. switching loops, VTP

  5. routing loops, STP

  6. switching loops, STP

Answer: F Explanation:

The Spanning-Tree Protocol (STP) prevents loops from being formed when switches or bridges are interconnected via multiple paths. Spanning-Tree Protocol implements the 802.1D IEEE algorithm by exchanging BPDU messages with other switches to detect loops, and then removes the loop by shutting down selected bridge interfaces. This algorithm guarantees that there is one and only one active path between two network devices.

Question No: 65 – (Topic 2)

Which switch would STP choose to become the root bridge in the selection process?

A. 32768: 11-22-33-44-55-66

B. 32768: 22-33-44-55-66-77

C. 32769: 11-22-33-44-55-65

D. 32769: 22-33-44-55-66-78

Answer: A Explanation:

The root bridge of the spanning tree is the bridge with the smallest (lowest) bridge ID. Each bridge has a configurable priority number and a MAC Address; the bridge ID contains both numbers combined together – Bridge priority MAC (32768.0200.0000.1111). The Bridge priority default is 32768 and can only be configured in multiples of 4096(Spanning tree uses the 12 bits extended system ID). To compare two bridge IDs, the priority is compared first, as if looking at a real number anything less than 32768…will become the target of being the root. If two bridges have equal priority then the MAC addresses are compared; for example, if switches A (MAC=0200.0000.1111) and B (MAC=0200.0000.2222) both have a priority of 32768 then switch A will be selected as the root bridge.

In this case, 32768: 11-22-33-44-55-66 would be the bridge because it has a lower priority and MAC address.

Question No: 66 – (Topic 2)

Refer to the exhibit.

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Each of these four switches has been configured with a hostname, as well as being configured to run RSTP. No other configuration changes have been made. Which three of these show the correct RSTP port roles for the indicated switches and interfaces? (Choose three.)

  1. SwitchA, Fa0/2, designated

  2. SwitchA, Fa0/1, root

  3. SwitchB, Gi0/2, root

  4. SwitchB, Gi0/1, designated

  5. SwitchC, Fa0/2, root

  6. SwitchD, Gi0/2, root

Answer: A,B,F Explanation:

The question says “no other configuration changes have been made” so we can understand these switches have the same bridge priority. Switch C has lowest MAC

address so it will become root bridge and 2 of its ports (Fa0/1 amp; Fa0/2) will be designated ports.

Because SwitchC is the root bridge so the 2 ports nearest SwitchC on SwitchA (Fa0/1) and SwitchD (Gi0/2) will be root ports.

Now we come to the most difficult part of this question: SwitchB must have a root port so which port will it choose? To answer this question we need to know about STP cost and port cost.

In general, “cost” is calculated based on bandwidth of the link. The higher the bandwidth on a link, the lower the value of its cost. Below are the cost values you should memorize:

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SwitchB will choose the interface with lower cost to the root bridge as the root port so we must calculate the cost on interface Gi0/1 amp; Gi0/2 of SwitchB to the root bridge. This can be calculated from the “cost to the root bridge” of each switch because a switch always advertises its cost to the root bridge in its BPDU. The receiving switch will add its local port cost value to the cost in the BPDU.

One more thing to notice is that a root bridge always advertises the cost to the root bridge (itself) with an initial value of 0.

Now let’s have a look at the topology again

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SwitchC advertises its cost to the root bridge with a value of 0. Switch D adds 4 (the cost value of 1Gbps link) and advertises this value (4) to SwitchB. SwitchB adds another 4 and learns that it can reach SwitchC via Gi0/1 port with a total cost of 8. The same process happens for SwitchA and SwitchB learns that it can reach SwitchC via Gi0/2 with a total cost of 23 -gt; Switch B chooses Gi0/1 as its root port -gt;.

Now our last task is to identify the port roles of the ports between SwitchA amp; SwitchB. It is rather easy as the MAC address of SwitchA is lower than that of SwitchB so Fa0/2 of SwitchA will be designated port while Gi0/2 of SwitchB will be alternative port.

Below summaries all the port roles of these switches:

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DP: Designated Port (forwarding state)

RP: Root Port (forwarding state)

AP: Alternative Port (blocking state)

Question No: 67 – (Topic 2)

Refer to the exhibit.

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At the end of an RSTP election process, which access layer switch port will assume the discarding role?

  1. Switch3, port fa0/1

  2. Switch3, port fa0/12

  3. Switch4, port fa0/11

  4. Switch4, port fa0/2

  5. Switch3, port Gi0/1

  6. Switch3, port Gi0/2

    Answer: C Explanation:

    In this question, we only care about the Access Layer switches (Switch3 amp; 4). Switch 3 has a lower bridge ID than Switch 4 (because the MAC of Switch3 is smaller than that of Switch4) so both ports of Switch3 will be in forwarding state. The alternative port will surely belong to Switch4.

    Switch4 will need to block one of its ports to avoid a bridging loop between the two switches. But how does Switch4 select its blocked port? Well, the answer is based on the BPDUs it receives from Switch3. A BPDU is superior to another if it has:

    1. A lower Root Bridge ID

    2. A lower path cost to the Root

    3. A lower Sending Bridge ID

    4. A lower Sending Port ID

      These four parameters are examined in order. In this specific case, all the BPDUs sent by Switch3 have the same Root Bridge ID, the same path cost to the Root and the same Sending Bridge ID. The only parameter left to select the best one is the Sending Port ID

      (Port ID = port priority port index). In this case the port priorities are equal because they use the default value, so Switch4 will compare port index values, which are unique to each port on the switch, and because Fa0/12 is inferior to Fa0/1, Switch4 will select the port connected with Fa0/1 (of Switch3) as its root port and block the other port -gt; Port fa0/11 of Switch4 will be blocked (discarding role).

      Question No: 68 – (Topic 2)

      VLAN 3 is not yet configured on your switch. What happens if you set the switchport access vlan 3 command in interface configuration mode?

      1. The command is rejected.

      2. The port turns amber.

      3. The command is accepted and the respective VLAN is added to vlan.dat.

      4. The command is accepted and you must configure the VLAN manually.

Answer: C Explanation:

The “switchport access vlan 3” will put that interface as belonging to VLAN 3 while also updated the VLAN database automatically to include VLAN 3.

Question No: 69 – (Topic 2)

What are three advantages of VLANs? (Choose three.)

  1. VLANs establish broadcast domains in switched networks.

  2. VLANs utilize packet filtering to enhance network security.

  3. VLANs provide a method of conserving IP addresses in large networks.

  4. VLANs provide a low-latency internetworking alternative to routed networks.

  5. VLANs allow access to network services based on department, not physical location.

  6. VLANs can greatly simplify adding, moving, or changing hosts on the network.

Answer: A,E,F

Explanation:

VLAN technology is often used in practice, because it can better control layer2 broadcast to improve network security. This makes network more flexible and scalable.

Packet filtering is a function of firewall instead of VLAN.

Question No: 70 – (Topic 2)

Refer to Exhibit:

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How many broadcast domains are shown in the graphic assuming only the default VLAN is configured on the switches?

  1. one

  2. two

  3. six

  4. twelve

Answer: A Explanation:

Only router can break up broadcast domains but in this exhibit no router is used so there is only 1 broadcast domain.

For your information, there are 7 collision domains in this exhibit (6 collision domains between hubs amp; switches 1 collision between the two switches).

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