The RSTP network shown in the figure, according to the configuration of SWC in the figure, it can be judged that the type of E0/1 port of SWC is? (Multiple choice)

Question

Options

• AEdge port
• BPreliminary port
• CDesignated port
• DRoot port

• A
  81% (43)
• B
  9% (5)
• C
  4% (2)
• D
  6% (3)

Explanation

In RSTP, an edge port is one configured to connect directly to an end-user device (like a PC) rather than to another switch. Because no BPDUs are expected on that link, it skips negotiation and transitions immediately to forwarding state - this behavior is enabled via PortFast or an explicit edge-type configuration, which the SWC figure shows applied to E0/1, making A correct.

B is wrong because "Preliminary port" is not a valid RSTP port type at all - it's a fabricated distractor, so eliminate it immediately if you see it on an exam. C (Designated port) describes a port role - the port on a segment responsible for forwarding toward end devices or downstream switches - which is a different classification axis from port type; the question specifically asks about type, and the edge configuration is the defining characteristic here. D (Root port) is the upstream-facing port on a non-root switch that has the best cost path back to the root bridge, which has nothing to do with an end-device-facing edge configuration.

Memory tip: Think E for End-device = Edge port. Whenever you see PortFast or edge-type edge in a switch config, the port faces an end host and is, by definition, an edge port - regardless of what else it might be doing in the topology.

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