CCNA Network Services and Security Practice Question
Exhibit
SW2# show spanning-tree vlan 10
Root ID Priority 32778
Address 0011.1111.1111
Cost 4
Port 1 (GigabitEthernet0/1)
Bridge ID Priority 32778
Address 00aa.aaaa.aaaaSW2 receives the following STP details for VLAN 10: The root bridge ID is 32768:0001.0001.0001 (SW1), and SW2's bridge ID is 32768:0002.0002.0002. Its interface Gi0/1 has a path cost of 4 to the root, while Gi0/2 has a path cost of 19. Based on this information, which statement is correct?
⚠ Common exam trap
A common exam trap is to incorrectly conclude that STP is disabled when bridge priorities are equal. Candidates may mistakenly believe that equal priorities cause STP to fail or not elect a root bridge. However, STP always elects a root bridge by comparing the MAC addresses as a tiebreaker when priorities match. Another trap is assuming all ports on a non-root switch must be designated ports, ignoring the existence of a root port that leads toward the root bridge. Misreading the root port can lead to incorrect answers about port roles and network topology.
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
✓
Gi0/1 on SW2 is the root port.
The root bridge has the lowest bridge ID. SW1 is the root because its bridge ID is lower than SW2's local bridge ID. On a non-root switch, the port with the best path toward the root becomes the root port, so Gi0/1 is the root port 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.
- ✗
SW2 is the root bridge for VLAN 10.
Why it's wrong here
SW2 cannot be the root bridge for VLAN 10 because the root identifier in the BPDU contains a bridge priority and MAC address that do not match SW2's own bridge ID. If SW2 were the root, its BPDU would advertise its own bridge ID as the root ID. Since the advertised root ID differs from SW2's local bridge ID, SW2 is a non-root switch.
When this WOULD be correct
In a different question scenario where the exhibit shows that SW2 has the lowest bridge ID among all switches in the VLAN, candidates would correctly identify that SW2 is the root bridge for VLAN 10, confirming its role in the STP topology.
- ✓
Gi0/1 on SW2 is the root port.
Why this is correct
Gi0/1 is the root port because STP selects the port with the lowest root path cost to reach the root bridge, and the received BPDU lists the root as reachable through Port 1. On SW2, Port 1 maps to Gi0/1, so that interface assumes the root port role. A root port is the non-root switch's closest path to the root, and it remains in forwarding state.
- ✗
All SW2 ports in VLAN 10 must be designated ports.
Why it's wrong here
Only the root bridge has all of its ports in the designated port role; a non-root switch like SW2 must have exactly one root port on the path toward the root. Other interfaces on SW2 may be alternate ports in the blocking state if they provide redundant paths, or they may be designated ports if they connect downstream segments. Therefore the statement that all SW2 VLAN 10 ports are designated ports is false.
When this WOULD be correct
In a different scenario where the question states that SW2 is the root bridge for VLAN 10, and all other switches in the topology have designated ports leading to SW2, then this option would be correct. This would imply that SW2's ports are indeed all designated due to its root bridge status.
- ✗
STP is disabled because the priorities are equal.
Why it's wrong here
Equal bridge priorities do not disable STP; the Spanning Tree Protocol continues to operate and uses the bridge MAC address as the tie-breaker when priorities match. The switch with the numerically lowest MAC address is elected as the root bridge. STP only stops running when explicitly disabled on the switch, not merely because two switches advertise the same priority value.
When this WOULD be correct
In a different exam scenario where the question specifies that all switches in the network have identical bridge priorities and no unique MAC addresses, one could conclude that STP is effectively disabled due to the lack of a definitive root bridge. The question would need to emphasize that no other STP parameters are available to break the tie.
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.
✓Gi0/1 on SW2 is the root port.Correct answer▾
Why this is correct
Gi0/1 is the root port because STP selects the port with the lowest root path cost to reach the root bridge, and the received BPDU lists the root as reachable through Port 1. On SW2, Port 1 maps to Gi0/1, so that interface assumes the root port role. A root port is the non-root switch's closest path to the root, and it remains in forwarding state.
✗SW2 is the root bridge for VLAN 10.Wrong answer — click to see why▾
Why this is wrong here
This option is incorrect because the question indicates that SW2 is not the root bridge for VLAN 10, as it is receiving STP details from another switch, implying that another switch has a lower bridge ID.
★ When this WOULD be the correct answer
In a different question scenario where the exhibit shows that SW2 has the lowest bridge ID among all switches in the VLAN, candidates would correctly identify that SW2 is the root bridge for VLAN 10, confirming its role in the STP topology.
Why candidates choose this
Candidates might choose this option due to a misunderstanding of STP roles, mistakenly believing that receiving STP details indicates that the switch is the root bridge, rather than recognizing the importance of bridge IDs in determining the root.
✗All SW2 ports in VLAN 10 must be designated ports.Wrong answer — click to see why▾
Why this is wrong here
This option is wrong because not all ports on a switch can be designated ports; at least one port must be a root port or a blocked port based on STP calculations. In the context of the given exhibit, SW2 cannot have all its VLAN 10 ports designated if it is not the root bridge.
★ When this WOULD be the correct answer
In a different scenario where the question states that SW2 is the root bridge for VLAN 10, and all other switches in the topology have designated ports leading to SW2, then this option would be correct. This would imply that SW2's ports are indeed all designated due to its root bridge status.
Why candidates choose this
Candidates may choose this option because they might confuse the roles of ports in STP, thinking that if a switch is functioning properly, all its ports must be designated. This reflects a misunderstanding of STP roles and their requirements.
✗STP is disabled because the priorities are equal.Wrong answer — click to see why▾
Why this is wrong here
This option is incorrect because STP cannot be disabled simply due to equal bridge priorities; it requires a tie-breaker based on MAC addresses or port IDs to determine the root bridge. In the context of the question, STP is still operational, and the root bridge is determined by the lowest bridge ID.
★ When this WOULD be the correct answer
In a different exam scenario where the question specifies that all switches in the network have identical bridge priorities and no unique MAC addresses, one could conclude that STP is effectively disabled due to the lack of a definitive root bridge. The question would need to emphasize that no other STP parameters are available to break the tie.
Why candidates choose this
Candidates may find this option tempting because they might misunderstand how STP operates and assume that equal priorities automatically lead to STP being disabled, overlooking the need for a tie-breaking mechanism.
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?”
Visual reference
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
Related to this question
Learn chapter
Device File Management with SFTP and SCP
Key term
VLAN
A VLAN logically segments a physical network into isolated broadcast domains without requiring separate physical switches.
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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JA
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.