Continue your lesson
Tie every forwarding decision to interface state, Layer 2 state, addressing, routing, and policy.
Block 1 of 3Compare Root bridge · Root port
Current · 14 min
Compare Root bridge · Root port
Optional concept notes
Root bridge
Provides the spanning-tree reference switch with the lowest bridge ID.
Root port
Provides a nonroot switch's lowest-cost path toward the root bridge.
Complete one provider lesson, then answer four related questions. That is enough for today; more practice is optional.
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Block 2 of 3Understand BPDU Guard
13 min
Understand BPDU Guard
Optional concept notes
BPDU Guard
Error-disables a PortFast edge port if it receives a spanning-tree BPDU.
Complete one provider lesson, then answer four related questions. That is enough for today; more practice is optional.
Your lesson stays open here while the provider opens in another tab. Choose one source; the notes above are optional.
Block 3 of 3Understand Root Guard
14 min
Understand Root Guard
Optional concept notes
Root Guard
Places a port in a root-inconsistent state after a superior BPDU so that port cannot become the root port while the condition remains.
Complete one provider lesson, then answer four related questions. That is enough for today; more practice is optional.
Your lesson stays open here while the provider opens in another tab. Choose one source; the notes above are optional.
Practice the reasoning here
Write or inspect a small Cisco configuration, name the expected show-command evidence, and explain how a frame or packet crosses it.
- State the expected result before changing or testing anything.
- Name the observation, command, log, or report that would confirm it.
- Explain why the closest alternative does not fit the same requirement.
Check the whole objective
This unlocks objective 2.5 for recall. The latest checkpoint needs 70% or higher; a lower result puts the lesson back near the front of your timeline.