Refer to the exhibit. Assuming all links are functional, which path does PC1 take to reach DSW1?

Question

Exhibits

Options

• APC1 goes from ALSW1 to DSW1
• BPC1 goes form ALSW1 to DSW2 to ALSW2 to DSW1
• CPC1 goes from ALSW1 to DSW2 to Core to DSW1
• DPC1 goes from ALSW1 to DSW2 to DSW1

• A
  2% (1)
• B
  9% (4)
• C
  15% (7)
• D
  74% (34)

Explanation

Option D is correct because in a typical hierarchical network design with Spanning Tree Protocol (STP), ALSW1's primary uplink to DSW1 is likely blocked to prevent loops, forcing traffic to traverse through DSW2 instead - and since DSW1 and DSW2 are distribution layer switches directly connected, the path logically flows ALSW1 → DSW2 → DSW1.

Option A is wrong because the direct link between ALSW1 and DSW1 is in a Spanning Tree blocked/discarding state to prevent a Layer 2 loop, so traffic cannot use that path even though it is physically functional. Option B is wrong because routing traffic back down to ALSW2 and then up to DSW1 would be an inefficient, non-optimal path that STP and routing protocols would never prefer over a direct distribution-layer link. Option C is wrong because involving the Core layer is unnecessary when DSW2 already has a direct connection to DSW1 - traffic only escalates to the Core when crossing between separate distribution blocks.

Memory Tip: Think of the rule "up once, across, down once" - in a collapsed/hierarchical design, traffic climbs to distribution (DSW2), crosses at that layer to the destination distribution switch (DSW1), and never unnecessarily bounces through access or core layers when a direct path exists.

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