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Difficulty: HardVLAN Configuration and Access Port Setup

A network administrator enters the following command sequence on interface GigabitEthernet0/5 of a Cisco Catalyst switch:

text
Switch(config)# interface GigabitEthernet0/5
Switch(config-if)# switchport mode access
Switch(config-if)# switchport access vlan 40

Prior to this configuration, VLAN 40 did not exist in the switch's VLAN database. Which TWO statements correctly describe the behavior and operational result of this configuration? (Select TWO.)

  1. VLAN 40 is automatically created in the switch VLAN database if it does not currently exist.Answer
  2. Interface GigabitEthernet0/5 is assigned to VLAN 40 and sends/receives untagged traffic for that VLAN.Answer
  3. C
    Interface GigabitEthernet0/5 adds an 802.1Q header tag to all outgoing Ethernet frames destined for connected end devices.
  4. D
    The switch automatically bridges broadcast traffic between VLAN 40 and VLAN 1 without needing a Layer 3 routing device.

Answer

VLAN 40 is automatically generated in the switch database if it was missing, and GigabitEthernet0/5 acts as an access port transmitting untagged frames within VLAN 40.
Executing 'switchport access vlan 40' automatically instantiates VLAN 40 in the switch database if it was not previously configured. Furthermore, setting an interface to access mode ensures it operates within a single VLAN and forwards standard untagged Ethernet frames to connected end-node devices.

Step-by-Step Solution

1
Analyze the command sequence applied to GigabitEthernet0/5.
The interface mode is explicitly set to access ('switchport mode access') and assigned to VLAN 40 ('switchport access vlan 40').
Determines the operating characteristics and membership of the interface.
2
Evaluate Cisco IOS automatic VLAN creation behavior.
Cisco IOS automatically generates VLAN 40 in the VLAN database if it does not already exist when assigned to an access port.
Prevents port assignment failure due to uninitialized VLAN IDs.
3
Evaluate framing behavior for an access port.
Access ports belong to exactly one VLAN and process untagged frames for host endpoints.
Host NICs typically do not recognize or process 802.1Q tagged frames.

Key Concept

VLAN Auto-creation and Access Port Framing Behavior
Estimated Time:1m 30s
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Topics

VLAN Configuration and Access Port Setup

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