CCNA Switching and Network Access Practice Question
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
⚠ Common exam trap
Remember, the root port is determined by the lowest path cost to the root bridge, not by any other criteria.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Root port
On a non-root switch, the port with the lowest path cost toward the root bridge becomes the root port. The higher-cost uplink would become an alternate (blocked) port. A designated port is found on the upstream switch toward this switch, not on the non-root switch itself. A disabled port is administratively shut down, which does not apply here.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Alternate port
Why it's wrong here
An alternate port is a backup to the root port; it receives a more favorable BPDU from a different switch on the same segment, but fails to beat the current root port's cost/tie-breakers. It remains in a discarding state, providing a secondary path to the root that can be used if the current root port fails. Thus, it is not the primary best path to the root, so it is incorrect for the question.
When this WOULD be correct
In a different scenario where a switch has multiple uplinks and one link fails, the remaining uplink with a higher cost could be designated as an alternate port, providing a backup path to the root bridge while the primary path is down.
- ✓
Root port
Why this is correct
The root port is selected on each non-root bridge by comparing received BPDUs; the port with the lowest cumulative root path cost (with tie-breaking rules) becomes the root port, placing it in the forwarding state. This is the port that provides the single best path toward the root bridge, carrying all upstream traffic. Since the non-root switch has two uplinks, the one with the lower cost to the root is the root port.
- ✗
Designated port
Why it's wrong here
A designated port is elected per collision domain/segment, representing the switch on that segment that has the best path to the root. On a segment connecting the non-root switch to the root, the designated port would be on the root side, not on the non-root switch; for other segments, the non-root switch may have designated ports for downstream switches, but those are not uplinks toward the root. In this scenario, the port facing the root on a non-root switch is a root port, not a designated port, because it is not the segment's forwarding decision—it is the switch's path to the root.
When this WOULD be correct
In a different scenario, if the question stated that a switch has multiple segments and one of the uplinks is the only connection to a segment with multiple switches, then that uplink could be designated if it has the lowest cost to the root bridge for that segment.
- ✗
Disabled port
Why it's wrong here
A disabled port is a port that is administratively shut down (shutdown command) or has failed hardware, so it cannot participate in spanning tree and does not forward traffic. Since the scenario describes an active, lower-cost uplink, a disabled port would be nonfunctional, and thus cannot be the correct role. The correct role must be in a forwarding state, which a disabled port never is.
When this WOULD be correct
In a different scenario, if a switch is configured with a specific port that has been administratively shut down or if the STP has determined that the port should not be used due to a loop or misconfiguration, the question might ask about the status of that port, making 'disabled port' the correct answer.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Root portCorrect answer▾
Why this is correct
The root port is selected on each non-root bridge by comparing received BPDUs; the port with the lowest cumulative root path cost (with tie-breaking rules) becomes the root port, placing it in the forwarding state. This is the port that provides the single best path toward the root bridge, carrying all upstream traffic. Since the non-root switch has two uplinks, the one with the lower cost to the root is the root port.
✗Alternate portWrong answer — click to see why▾
Why this is wrong here
An alternate port is a backup path to the root bridge that is not currently in use. In this scenario, the lower-cost uplink is actively forwarding traffic as the root port, making 'alternate port' an incorrect designation.
★ When this WOULD be the correct answer
In a different scenario where a switch has multiple uplinks and one link fails, the remaining uplink with a higher cost could be designated as an alternate port, providing a backup path to the root bridge while the primary path is down.
Why candidates choose this
Candidates may confuse the roles of ports in STP, especially if they focus on the presence of multiple uplinks and mistakenly associate lower-cost paths with alternate roles instead of recognizing the active forwarding role of the root port.
✗Designated portWrong answer — click to see why▾
Why this is wrong here
The designated port is the port on a network segment that has the lowest cost to the root bridge and is responsible for forwarding traffic towards the root. In this case, the question specifies a non-root switch with two uplinks, where the lower-cost uplink is the root port, not a designated port.
★ When this WOULD be the correct answer
In a different scenario, if the question stated that a switch has multiple segments and one of the uplinks is the only connection to a segment with multiple switches, then that uplink could be designated if it has the lowest cost to the root bridge for that segment.
Why candidates choose this
Candidates might confuse the roles of ports in STP, thinking that any port involved in forwarding traffic could be designated, especially if they overlook the specific context of uplinks and cost comparisons.
✗Disabled portWrong answer — click to see why▾
Why this is wrong here
A disabled port is not actively participating in the Spanning Tree Protocol (STP) and cannot forward traffic. In the context of the question, the lower-cost uplink would be actively used as the root port, not disabled.
★ When this WOULD be the correct answer
In a different scenario, if a switch is configured with a specific port that has been administratively shut down or if the STP has determined that the port should not be used due to a loop or misconfiguration, the question might ask about the status of that port, making 'disabled port' the correct answer.
Why candidates choose this
Candidates may confuse the concept of port states in STP and mistakenly think that a lower-cost path could be disabled due to misconfigurations or administrative actions, leading them to choose this option.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Key term
Root bridge
The root bridge is the central reference point in a Spanning Tree Protocol (STP) network, serving as the logical root of the spanning tree topology.
Key term
Root port
A root port is the port on a non-root switch in a Spanning Tree Protocol network that has the lowest cost path to the root bridge.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.