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Switch Questions 2

May 23rd, 2017 Go to comments

Question 1

Explanation

When you connect an IP phone to a switch using a trunk link, it can cause high CPU utilization in the switches. As all the VLANs for a particular interface are trunked to the phone, it increases the number of STP instances the switch has to manage. This increases the CPU utilization. Trunking also causes unnecessary broadcast / multicast / unknown unicast traffic to hit the phone link.

In order to avoid this, remove the trunk configuration and keep the voice and access VLAN configured along with Quality of Service (QoS). Technically, it is still a trunk, but it is called a Multi-VLAN Access Port (MVAP). Because voice and data traffic can travel through the same port, you should specify a different VLAN for each type of traffic. You can configure a switch port to forward voice and data traffic on different VLANs. Configure IP phone ports with a voice VLAN configuration. This configuration creates a pseudo trunk, but does not require you to manually prune the unnecessary VLANs.

The voice VLAN feature enables access ports to carry IP voice traffic from an IP phone. You can configure a voice VLAN with the “switchport voice vlan …” command under interface mode. The full configuration is shown below:

Switch(config)#interface fastethernet0/1
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 10
Switch(config-if)#switchport voice vlan 20

Reference: http://www.cisco.com/c/en/us/support/docs/switches/catalyst-4500-series-switches/69632-configuring-cat-ip-phone.html

Question 2

Explanation

To remote access to SwitchB, it must have a management IP address on a VLAN on that switch. Traditionally, we often use VLAN 1 as the management VLAN (but in fact it is not secure).

In the exhibit, we can recognize that the Management Workstation is in a different subnet from the SwitchB. For intersubnetwork communication to occur, you must configure at least one default gateway. This default gateway is used to forward traffic originating from the switch only, not to forward traffic sent by devices connected to the switch.

Question 3

Explanation

Microsegmentation is a network design (functionality) where each workstation or device on a network gets its own dedicated segment (collision domain) to the switch. Each network device gets the full bandwidth of the segment and does not have to share the segment with other devices. Microsegmentation reduces and can even eliminate collisions because each segment is its own collision domain -> A is correct.

Note: Microsegmentation decreases the number of collisions but it increases the number of collision domains.

D and E are correct based on the theory of STP and VLAN.

Question 4

Question 5

Explanation

The MAC address of 00b0.d056.efa4 has not been learned in its MAC address table so Switch-1 will broadcast the frame out all of its ports except the port from which the data originated.

Question 6

Explanation

“ping” command is used to send echo requests and receive echo replies.

Question 7

Question 8

Explanation

We can check the MAC address table with the command “show mac address-table”:

show_mac_address-table.jpg

As we can see here, the “MAC address” field is the source MAC address and the “Ports” field are the ports of the switch from which the frames (with corresponding source MAC address) were received.

Question 9

Explanation

To switch frames between LAN ports efficiently, the switch maintains an address table. When the switch receives a frame, it associates the media access control (MAC) address of the sending network device with the LAN port on which it was received.

The switch dynamically builds the address table by using the MAC source address of the frames received. When the switch receives a frame for a MAC destination address not listed in its address table, it floods the frame to all LAN ports of the same VLAN except the port that received the frame. When the destination station replies, the switch adds its relevant MAC source address and port ID to the address table. The switch then forwards subsequent frames to a single LAN port without flooding all LAN ports.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/configuration/guide/cli/CLIConfigurationGuide/MACAddress.html

When the switch dynamically builds the MAC address table, it also specifies the time before an entry ages out and is discarded from the MAC address table. The default is 300 seconds.

Question 10

Question 11

Comments (11) Comments
  1. Michael
    June 13th, 2017

    Passed today, used the 747q dumps. you can find them on https://drive.google.com/open?id=0B5mAFqgydmCzc3BmR214LWFuTDg

  2. Reginald
    June 19th, 2017

    Thanks Michael, the dumps are valid.

  3. Viyasar
    July 4th, 2017

    For question 6
    Isn’t it supposed to send ARP request through all ports, learn the MAC address and then forward the packet?

  4. Viyasar
    July 7th, 2017

    For question 5
    Isn’t it supposed to send ARP request through all ports, learn the MAC address and then forward the packet?

  5. Becky
    July 8th, 2017

    Q5
    It is Arp or broadcast

  6. Anony
    July 11th, 2017

    ARP is a layer 3 thing. Switches behave using Layer 2 protocols only so it does not send an ARP request for unknown MAC addresses. It just sends the frame out through all ports except for the port the frame came in on.

  7. samadi
    August 7th, 2017

    under normal operation, cisco recomends u configure switchpot on which on which vlan
    a: on any vlan accept default vlan
    b: on the management vlan
    c:on the native vlan
    D:on the default vlan

  8. Altaie
    August 11th, 2017

    Q10 as i remember, we should either :
    – set both sides to half duplex
    – set both sides to autonegotiate
    – set one side to autonegotiate and other side to half duplex
    so the answer is C,E,F

    can you double check this please ?

  9. Anonymous
    August 22nd, 2017

    Where are the questions? i see the answers only , please help me thanks

  10. kari
    August 31st, 2017

    @Anonymous
    Questions can be found at http://www.9tut.com/ccna-questions-and-answers

  11. vincent
    September 7th, 2017

    reginald cn u pls send me the dumps pls or any1 who has the valid dumps i realy wana get over these.. my certificates has expired pls help.. my email is {email not allowed}

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