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Switching and VLANs

You’ll be able to

Switching and VLANs

A switch learns which MAC addresses appear on each port and forward frames accordingly. VLANs create separate logical broadcast domains on shared switching hardware. Traffic between VLANs requires routing and can be governed by access policy.

Decision lens

Strong technical decisions connect evidence → mechanism → impact → response. Identify what the evidence shows, explain the system behavior that produced it, state the likely effect on people or data, and choose a response that addresses the cause without creating unnecessary disruption.

Worked example

Student and payroll devices plug into the same switches, and broadcasts from either group reach the other.

  1. 1.The current design places both groups in one broadcast domain.
  2. 2.Create separate student and payroll VLANs.
  3. 3.Use a trunk for tagged VLAN traffic between switches.
  4. 4.Apply routing and firewall rules so only required services cross the boundary.
Answer: VLANs provide segmentation, but policy at the routed boundary determines what communication is allowed.
Checkpoint

What is required for hosts in different VLANs to communicate?

Checkpoint

Which response best demonstrates complete reasoning about Layer 2 forwarding and logical segmentation?

On the exam

For a scenario about Layer 2 forwarding and logical segmentation, identify the decisive evidence before naming a response. A defensible conclusion here is: VLANs provide segmentation, but policy at the routed boundary determines what communication is allowed.

Answer the 2 checkpoints as you read.

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