CCNA Switching and Network Access Practice Question
This 200-301 practice question tests your understanding of switching and network access. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
SW1# show etherchannel load-balance
EtherChannel Load-Balancing Configuration:
src-mac
EtherChannel Load-Balancing Addresses Used Per-Protocol:
Non-IP: Source MAC address
IPv4: Source MAC address
IPv6: Source MAC address
Load-Balancing Operational Parameters:
Hash algorithm: CRC
Asymmetric hashing: disabled
Refer to the exhibit. A network engineer notices that on a four-link EtherChannel bundle between two switches, all traffic from a particular VLAN is being forwarded over only one physical link, while the other three links remain idle. The engineer suspects a load-balancing issue and issues the show etherchannel load-balance command, the output of which is shown. What is the most likely cause of the uneven traffic distribution?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
SW1# show etherchannel load-balance
EtherChannel Load-Balancing Configuration:
src-mac
EtherChannel Load-Balancing Addresses Used Per-Protocol:
Non-IP: Source MAC address
IPv4: Source MAC address
IPv6: Source MAC address
Load-Balancing Operational Parameters:
Hash algorithm: CRC
Asymmetric hashing: disabled
A
The switch is using source‑MAC‑address load balancing, and multiple end hosts are appearing with the same source MAC address.
The show etherchannel load-balance output confirms the global load‑balancing method is src‑mac. With this method, frames with an identical source MAC always hash to the same physical member link, causing all traffic from hosts sharing that MAC to use only one link.
B
The EtherChannel is misconfigured with an LACP active/passive mode mismatch, forcing only one link to bundle.
Why wrong: An LACP mode mismatch prevents the EtherChannel from coming up at all; it would not show a formed bundle with only one active link. The exhibit does not display LACP state, only the load‑balancing algorithm.
C
VLAN pruning on the trunk has removed the VLAN from three of the four member interfaces.
Why wrong: VLAN pruning controls which VLAN traffic is allowed on a trunk. If the VLAN were removed from three members, those members would not carry any traffic for that VLAN, but they would still carry other VLANs and would not be idle for all traffic. The exhibit does not mention VLAN pruning.
D
Spanning Tree Protocol has blocked three of the four links in the EtherChannel because they form a loop.
Why wrong: STP treats a correctly configured EtherChannel as a single logical interface. Unless there is a misconfiguration (e.g., port‑channel members in different STP states), all members should share the same STP state. The exhibit shows no STP information, and a blocked state would not be caused by the load‑balancing setting.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The switch is using source‑MAC‑address load balancing, and multiple end hosts are appearing with the same source MAC address.
The exhibit shows the load-balancing method is 'src-mac'. When source-MAC-based hashing is used, all frames with the same source MAC address egress the same physical member link. If multiple end hosts are behind a router or proxy and appear with identical source MAC, the hash algorithm always selects the same link, leaving the other links in the bundle idle.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The switch is using source‑MAC‑address load balancing, and multiple end hosts are appearing with the same source MAC address.
Why this is correct
The show etherchannel load-balance output confirms the global load‑balancing method is src‑mac. With this method, frames with an identical source MAC always hash to the same physical member link, causing all traffic from hosts sharing that MAC to use only one link.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.
✗
The EtherChannel is misconfigured with an LACP active/passive mode mismatch, forcing only one link to bundle.
Why it's wrong here
An LACP mode mismatch prevents the EtherChannel from coming up at all; it would not show a formed bundle with only one active link. The exhibit does not display LACP state, only the load‑balancing algorithm.
✗
VLAN pruning on the trunk has removed the VLAN from three of the four member interfaces.
Why it's wrong here
VLAN pruning controls which VLAN traffic is allowed on a trunk. If the VLAN were removed from three members, those members would not carry any traffic for that VLAN, but they would still carry other VLANs and would not be idle for all traffic. The exhibit does not mention VLAN pruning.
✗
Spanning Tree Protocol has blocked three of the four links in the EtherChannel because they form a loop.
Why it's wrong here
STP treats a correctly configured EtherChannel as a single logical interface. Unless there is a misconfiguration (e.g., port‑channel members in different STP states), all members should share the same STP state. The exhibit shows no STP information, and a blocked state would not be caused by the load‑balancing setting.
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.
✓The switch is using source‑MAC‑address load balancing, and multiple end hosts are appearing with the same source MAC address.Correct answer▾
Why this is correct
The show etherchannel load-balance output confirms the global load‑balancing method is src‑mac. With this method, frames with an identical source MAC always hash to the same physical member link, causing all traffic from hosts sharing that MAC to use only one link.
✗The EtherChannel is misconfigured with an LACP active/passive mode mismatch, forcing only one link to bundle.Wrong answer — click to see why▾
Why this is wrong here
Candidates may think that an LACP problem explains a single active link, but a mismatch would cause the entire EtherChannel to fail, not selectively use one member.
✗VLAN pruning on the trunk has removed the VLAN from three of the four member interfaces.Wrong answer — click to see why▾
Why this is wrong here
Candidates might mistake an idle member for a pruned VLAN, but pruning would not affect all traffic, only the specific VLAN, and it is not related to the load‑balance method shown.
✗Spanning Tree Protocol has blocked three of the four links in the EtherChannel because they form a loop.Wrong answer — click to see why▾
Why this is wrong here
Candidates may associate an idle link with STP blocking, but an EtherChannel bundle presents one logical link to STP. A blocking state on some members only would indicate a serious configuration error, not the load‑balance method shown.
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?”
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Trap categories for this question
Command / output trap
An LACP mode mismatch prevents the EtherChannel from coming up at all; it would not show a formed bundle with only one active link. The exhibit does not display LACP state, only the load‑balancing algorithm.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
Access ports place end devices into a single VLAN.
Trunk ports carry multiple VLANs between switches.
Allowed VLAN lists decide which VLANs can cross a trunk.
Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
→Use show vlan brief to verify access VLANs.
→Use show interfaces trunk to verify trunk state and allowed VLANs.
→Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 200-301 questions on switching, trunking, and access-port configuration.
Switching and Network Access — This question tests Switching and Network Access — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: The switch is using source‑MAC‑address load balancing, and multiple end hosts are appearing with the same source MAC address. — The exhibit shows the load-balancing method is 'src-mac'. When source-MAC-based hashing is used, all frames with the same source MAC address egress the same physical member link. If multiple end hosts are behind a router or proxy and appear with identical source MAC, the hash algorithm always selects the same link, leaving the other links in the bundle idle.
What should I do if I get this 200-301 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 200-301 questions on switching, trunking, and access-port configuration.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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