Home > ICND1 – Switch Questions 2

ICND1 – Switch Questions 2

June 24th, 2017 in ICND1 100-105 Go to comments

Question 1

Explanation

In this case the destination MAC address has been learned so the switch just forwards the frame to the corresponding port. It also learn that the source MAC address of host A has not been existed in the MAC address table so it will add it (and port fa0/3) to its MAC address table.

Question 2

Question 3

Explanation

All ports on a Layer 2 switch are in the same broadcast domain. Only router ports separate broadcast domains.

Question 4

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 5

Explanation

When a switch receives a frame, it first checks for the destination MAC address and tries to find a matching entry in its MAC address table. If found, the switch then forwards that frame on the corresponding port associated with that MAC address. If no entry is found, the switch will flood that frame out of all (active) ports except the port that sent it.

Question 6

Explanation

The system LED shows whether the system is receiving power and functioning properly. Below lists the LED colors and meanings:

Color System Status
Off System is not powered up.
Green System is operating normally.
Amber System is receiving power but is not functioning properly.

(Reference: http://www.cisco.com/en/US/docs/switches/lan/catalyst2950/hardware/installation/guide/hgovrev.html)

Question 7

Explanation

The “!” is an invalid letter for a hostname.

Question 8

Explanation

When a switch receives a frame, it first checks for the destination MAC address and tries to find a matching entry in its MAC address table. If found, the switch then forwards that frame on the corresponding port associated with that MAC address. If no entry is found, the switch will flood that frame out of all active ports except the port that sent it. In this case, the destination MAC address 0000.00dd.dddd has not been in the MAC address table so the switch will flood the frame out all of its ports except fa0/0 (the port that it received the frame) -> D is correct.

Also, the switch learns that the MAC address 0000.00aa.aaaa is received on fa0/0 -> the switch adds 0000.00aa.aaaa and its corresponding port fa0/0 to the MAC address table -> A is correct.

Question 9

Explanation

In short, TCAM (Ternary Content Addressable Memory) is used for faster IP look up while ARP table is Layer3 address to Layer2 address resolution so they are not correct.

The Content Addressable Memory (CAM) table on a switch keeps track of MAC addresses and on what port they appear, along with some other stuff like age. When a device that’s plugged into a particular port sends a frame to the switch, the switch makes note of the source MAC and the port and checks the CAM table. Notice that the CAM table is built on the source MAC addresses (while the destination MAC addresses are ignored).

Comments (6) Comments
  1. Lackadaisical_Cisco
    July 27th, 2017

    “CAM table is built on the source MAC addresses” what does it mean? “source MAC address” is not a device

  2. MacFs
    July 27th, 2017

    Source MAC addresses are attributes of the devices that communicate with switches. When devices connected to a switch attempt to comminicate through that switch (for multiple purposes), the switch will remember their MAC addresses. So no, “source MAC address” is not a device, but devices have (source) MAC addresses.

  3. will
    July 27th, 2017

    Which option is a invalid hostname for a switch?

    A. 5witch-Cisco
    B. Switch-Cisco!
    C. 5witchCisc0
    D. SwitchCisc0

    Answer: B

    Explanation

    The “!” is an invalid letter for a hostname.

    Please explain how I can configure all of those hostnames on my cisco switch.

  4. Natalie
    July 30th, 2017

    configuration:
    enable
    config terminal
    hostname 5with-Cisco etc

  5. Natalie
    July 30th, 2017

    or to be more specific
    R>enable
    R#configurate terminal
    R(conf)#hostname 5with-Cisco
    5with-Cisco(conf)#
    that’s how you will see it in your router CLI promt

  6. Anonymous
    August 2nd, 2017

    he means he can config it with the “!” Natalie when it states its invalid.

    In their naming conventions Will, they state this is wrong