The answer is that mismatched switchport modes between the member links are the most likely reason for the EtherChannel failure. This is because EtherChannel enforces strict consistency rules across all candidate interfaces; if one link is configured as an access port and another as a trunk, the channel cannot form, as the protocol sees conflicting Layer 2 behaviors. On the CCNA 200-301 v2 exam, this tests your understanding of the “consistency check” that EtherChannel performs before bundling links—a classic trap where engineers focus on the channel-group number or PAgP/LACP settings but overlook basic interface modes. Remember the memory tip: “Same speed, same duplex, same VLAN, same mode—if any differ, the channel won’t load.” Always verify that all member interfaces share identical switchport configurations, including trunking state and allowed VLANs, to avoid this common failure scenario.
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. A key principle to apply: etherChannel bundles multiple physical links into one logical link to increase bandwidth and provide redundancy in Cisco networks.. 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
interface GigabitEthernet0/1
switchport mode trunk
channel-group 1 mode active
interface GigabitEthernet0/2
switchport mode access
channel-group 1 mode active
A network engineer is configuring an EtherChannel between two switches. After applying the configuration, the port-channel fails to form. What is the most likely reason?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The member links use different switchport modes, so the channel cannot form correctly.
The port-channel is not forming because the two member interfaces are not configured consistently. In practical terms, EtherChannel requires important characteristics to align across candidate member links. Here, one interface is a trunk and the other is configured as an access port, so the channel cannot be built cleanly.
This is a classic EtherChannel consistency problem. The protocol alone is not enough if the member-link settings disagree.
Key principle: EtherChannel bundles multiple physical links into one logical link to increase bandwidth and provide redundancy in Cisco networks.
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 member links use different switchport modes, so the channel cannot form correctly.
Why this is correct
This is correct because trunk/access inconsistency breaks EtherChannel compatibility.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
EtherChannel bundles multiple physical links into one logical link to increase bandwidth and provide redundancy in Cisco networks.
✗
LACP requires both interfaces to use different channel-group numbers.
Why it's wrong here
This is wrong because member interfaces in the same bundle use the same channel-group number.
When this WOULD be correct
In a different scenario, if a question asked about a misconfiguration where two interfaces were incorrectly assigned to different channel-group numbers while trying to form a port-channel, this option would be correct. The question would need to specify that the interfaces are intended to be aggregated but are configured incorrectly.
✗
The interfaces must both be configured for PPP.
Why it's wrong here
This is wrong because PPP is unrelated to switch EtherChannel configuration.
When this WOULD be correct
In a different scenario where the question specifies that the interfaces are intended to connect over a WAN link using PPP and are part of a port-channel, then this option could be correct. For instance, if the question states that both interfaces must support PPP for proper encapsulation, this would validate the claim.
✗
The bundle fails because BGP is not enabled on the switch.
In a different question setup, if the context involved a scenario where BGP was explicitly required for establishing a specific type of connection or routing policy between switches, then this option could be correct. For example, if the question asked about the prerequisites for a BGP session over a port-channel, this option might apply.
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 member links use different switchport modes, so the channel cannot form correctly.Correct answer▾
Why this is correct
This is correct because trunk/access inconsistency breaks EtherChannel compatibility.
✗LACP requires both interfaces to use different channel-group numbers.Wrong answer — click to see why▾
Why this is wrong here
LACP requires that all member interfaces in the same port-channel use the same channel-group number. Using different numbers would place them in separate bundles, preventing the intended aggregation.
★ When this WOULD be the correct answer
In a different scenario, if a question asked about a misconfiguration where two interfaces were incorrectly assigned to different channel-group numbers while trying to form a port-channel, this option would be correct. The question would need to specify that the interfaces are intended to be aggregated but are configured incorrectly.
Why candidates choose this
Students may confuse the requirement for consistent channel-group numbers with the idea that different numbers are needed for load balancing or protocol operation, but in reality, all members of a single EtherChannel must share the same channel-group number.
✗The interfaces must both be configured for PPP.Wrong answer — click to see why▾
Why this is wrong here
PPP is a Layer 2 encapsulation used on serial links, not on Ethernet switch ports. EtherChannel on Cisco switches uses Ethernet frames, and PPP is irrelevant to the configuration of port-channels.
★ When this WOULD be the correct answer
In a different scenario where the question specifies that the interfaces are intended to connect over a WAN link using PPP and are part of a port-channel, then this option could be correct. For instance, if the question states that both interfaces must support PPP for proper encapsulation, this would validate the claim.
Why candidates choose this
A student might associate PPP with link aggregation protocols like Multilink PPP (MLPPP) used on WAN interfaces, and incorrectly assume it applies to Ethernet EtherChannel.
✗The bundle fails because BGP is not enabled on the switch.Wrong answer — click to see why▾
Why this is wrong here
BGP is a routing protocol that operates at Layer 3 and is not required for EtherChannel formation. EtherChannel is a Layer 2 technology that bundles physical links into a single logical link, independent of any routing protocol.
★ When this WOULD be the correct answer
In a different question setup, if the context involved a scenario where BGP was explicitly required for establishing a specific type of connection or routing policy between switches, then this option could be correct. For example, if the question asked about the prerequisites for a BGP session over a port-channel, this option might apply.
Why candidates choose this
Students may think that because BGP is used in complex network designs, it might be a prerequisite for advanced features like EtherChannel, but BGP has no role in the link aggregation process.
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: answer the scenario, not the keyword
Always verify interface configurations for consistency when troubleshooting EtherChannel issues.
Detailed technical explanation
How to think about this question
EtherChannel is a technology that bundles multiple physical Ethernet links into a single logical link to increase bandwidth and provide redundancy. Cisco switches use protocols like LACP (Link Aggregation Control Protocol) or PAgP (Port Aggregation Protocol) to negotiate and maintain these bundles. For EtherChannel to form correctly, all member interfaces must share consistent configurations, including speed, duplex, VLAN membership, and switchport mode (access or trunk). Any mismatch in these parameters prevents the logical aggregation from establishing, causing the port-channel to remain down or inactive.
The decision process for forming an EtherChannel involves verifying that all candidate interfaces have identical settings. Specifically, the switchport mode must be consistent across all member links; mixing trunk and access modes breaks the channel formation. LACP requires that all interfaces in the same channel-group use the same channel-group number and mode, but it does not allow differing switchport modes. This consistency check ensures that traffic is handled uniformly across the bundle, preventing frame loss or misrouting.
A common exam trap is to confuse protocol requirements or unrelated features with EtherChannel formation rules. For example, some might incorrectly believe that enabling routing protocols like BGP or configuring PPP on interfaces affects EtherChannel, but these are unrelated. The practical behavior is that even if LACP is enabled and channel-group numbers match, inconsistent switchport modes will prevent the port-channel from forming. Understanding this helps avoid misdiagnosing EtherChannel issues in real networks and on the exam.
KKey Concepts to Remember
EtherChannel bundles multiple physical links into one logical link to increase bandwidth and provide redundancy in Cisco networks.
All member interfaces in an EtherChannel must have identical switchport modes, either all trunk or all access, to form the channel correctly.
LACP requires member interfaces to share the same channel-group number and mode but does not allow differing switchport modes.
Inconsistent switchport modes between member links cause EtherChannel formation to fail due to incompatible VLAN tagging and traffic handling.
EtherChannel formation depends on physical and logical parameter consistency, including speed, duplex, VLAN membership, and switchport mode.
Routing protocols like BGP and Layer 2 protocols like PPP do not influence EtherChannel formation or operation.
Cisco switches use protocols like LACP or PAgP to negotiate EtherChannel, but protocol alone cannot override configuration mismatches.
EtherChannel consistency checks prevent traffic loss and misrouting by ensuring uniform handling of frames across all bundled links.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
EtherChannel bundles multiple physical links into one logical link to increase bandwidth and provide redundancy in Cisco networks.
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 etherChannel bundles multiple physical links into one logical link to increase bandwidth and provide redundancy in Cisco networks., then practise related 200-301 questions on the same topic to reinforce the concept.
Switching and Network Access — This question tests Switching and Network Access — EtherChannel bundles multiple physical links into one logical link to increase bandwidth and provide redundancy in Cisco networks..
What is the correct answer to this question?
The correct answer is: The member links use different switchport modes, so the channel cannot form correctly. — The port-channel is not forming because the two member interfaces are not configured consistently. In practical terms, EtherChannel requires important characteristics to align across candidate member links. Here, one interface is a trunk and the other is configured as an access port, so the channel cannot be built cleanly.
This is a classic EtherChannel consistency problem. The protocol alone is not enough if the member-link settings disagree.
What should I do if I get this 200-301 question wrong?
Review etherChannel bundles multiple physical links into one logical link to increase bandwidth and provide redundancy in Cisco networks., then practise related 200-301 questions on the same topic to reinforce the concept.
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?
EtherChannel bundles multiple physical links into one logical link to increase bandwidth and provide redundancy in Cisco networks.
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