Module 3 VLAN New

Under which two occasions should an administrator disable DTP while managing a local area network? (Choose two.)

• • when connecting a Cisco switch to a non-Cisco switch

  
  

• • when a neighbor switch uses a DTP mode of dynamic auto

  
  

• • when a neighbor switch uses a DTP mode of dynamic desirable

  
  

• • on links that should not be trunking

  
  

• • on links that should dynamically attempt trunking

  
  

Answer explanation

• Cisco best practice recommends disabling DTP on links where trunking is not intended and when a Cisco switch is connected to a non-Cisco switch. DTP is required for dynamic trunk negotiation.

Which two characteristics describe the native VLAN? (Choose two.)

• • Designed to carry traffic that is generated by users, this type of VLAN is also known as the default VLAN.

  
  

• • The native VLAN traffic will be untagged across the trunk link.

  
  

• • This VLAN is necessary for remote management of a switch.

  
  

• • High priority traffic, such as voice traffic, uses the native VLAN.

  
  

• • The native VLAN provides a common identifier to both ends of a trunk.

  
  

Answer explanation

• The native VLAN is assigned to 802.1Q trunks to provide a common identifier to both ends of the trunk link. Whatever VLAN native number is assigned to a port, or if the port is the default VLAN of 1, the port does not tag any frame in that VLAN as the traffic travels across the trunk. At the other end of the link, the receiving device that sees no tag knows the specific VLAN number because the receiving device must have the exact native VLAN number. The native VLAN should be an unused VLAN that is distinct from VLAN1, the default VLAN, as well as other VLANs. Data VLANs, also known as user VLANs, are configured to carry user-generated traffic, with the exception of high priority traffic, such as VoIP. Voice VLANs are configured for VoIP traffic. The management VLAN is configured to provide access to the management capabilities of a switch.

On a switch that is configured with multiple VLANs, which command will remove only VLAN 100 from the switch?

• • Switch# delete flash:vlan.dat

  
  

• • Switch(config-if)# no switchport access vlan 100

  
  

• • Switch(config-if)# no switchport trunk allowed vlan 100

  
  

• • Switch(config)# no vlan 100

  
  

Answer explanation

• To remove all VLANs from a switch, the delete flash:vlan.dat command would be used. To change the assigned VLAN for an interface, the no switchport access vlan 100 interface configuration command would be used. To remove VLAN 100 as an allowed VLAN on a trunk, the no switchport trunk allowed vlan 100 would be used, but this would not remove the VLAN from the switch. To delete a single VLAN, such as VLAN 100, the no vlan 100 global configuration command would be used.

Refer to the exhibit. A network administrator is reviewing port and VLAN assignments on switch S2 and notices that interfaces Gi0/1 and Gi0/2 are not included in the output. Why would the interfaces be missing from the output?

• • There is a native VLAN mismatch between the switches.

  
  

• • There is no media connected to the interfaces.

  
  

• • They are administratively shut down.

  
  

• • They are configured as trunk interfaces.

  
  

Answer explanation

• Interfaces that are configured as trunks do not belong to a VLAN and therefore will not show in the output of the show vlan brief commands.

A network contains multiple VLANs spanning multiple switches. What happens when a device in VLAN 20 sends a broadcast Ethernet frame?

• • All devices in all VLANs see the frame.

  
  

• • Devices in VLAN 20 and the management VLAN see the frame.

  
  

• • Only devices in VLAN 20 see the frame.

  
  

• • Only devices that are connected to the local switch see the frame.

  
  

Answer explanation

• VLANs create logical broadcast domains that can span multiple VLAN segments. Ethernet frames that are sent by a device on a specific VLAN can only be seen by other devices in the same VLAN.

A network contains multiple VLANs spanning multiple switches. What happens when a device in VLAN 20 sends a broadcast Ethernet frame?

• • All devices in all VLANs see the frame.

  
  

• • Devices in VLAN 20 and the management VLAN see the frame.

  
  

• • Only devices in VLAN 20 see the frame.

  
  

• • Only devices that are connected to the local switch see the frame.

  
  

Answer explanation

• VLANs create logical broadcast domains that can span multiple VLAN segments. Ethernet frames that are sent by a device on a specific VLAN can only be seen by other devices in the same VLAN.

Refer to the exhibit. All workstations are configured correctly in VLAN 20. Workstations that are connected to switch SW1 are not able to send traffic to workstations on SW2. What could be done to remedy the problem?

• Allow VLAN 20 on the trunk link.

• • Enable DTP on both ends of the trunk.

  
  

• • Configure all workstations on SW1 to be part of the default VLAN.

  
  

• • Configure all workstations on SW2 to be part of the native VLAN.

  
  

Answer explanation

• Enabling DTP on both switches simply allows negotiation of trunking. The "Negotiation of Trunking" line in the graphic shows that DTP is already enabled. The graphic also shows how the native VLAN is 1, and the default VLAN for any Cisco switch is 1. The graphic shows the PCs are to be in VLAN 20.

What happens to switch ports after the VLAN to which they are assigned is deleted?

• The ports are disabled.

• The ports are placed in trunk mode.

• The ports are assigned to VLAN1, the default VLAN.

• 
  The ports stop communicating with the attached devices.

Answer explanation

• The affected ports must be reconfigured for an active VLAN.

Refer to the exhibit. In what switch mode should port G0/1 be assigned if Cisco best practices are being used?

• 
  access

• 
  trunk

• 
  native

• 
  auto

Answer explanation

• The router is used to route between the two VLANs, thus switch port G0/1 needs to be configured in trunk mode.

Port Fa0/11 on a switch is assigned to VLAN 30. If the command no switchport access vlan 30 is entered on the Fa0/11 interface, what will happen?

• 
  Port Fa0/11 will be shutdown.

• 
  An error message would be displayed.

• Port Fa0/11 will be returned to VLAN 1.

• 
  VLAN 30 will be deleted.

Answer explanation

• When the no switchport access vlan command is entered, the port is returned to the default VLAN 1. The port will remain active as a member of VLAN 1, and VLAN 30 will still be intact, even if no other ports are associated with it.