CCNA Switching and Network Access Practice Question
Network Topology
Two switches are connected using four Gigabit Ethernet interfaces configured as an EtherChannel with LACP. The network administrator notices that only two of the four interfaces are active in the port-channel, and the other two are in a suspended state. Upon further investigation, the administrator finds that the two inactive interfaces correspond to remote interfaces that are configured with the 'on' mode, while the active ones correspond to remote interfaces configured with LACP active/passive. The administrator also verifies that all local interfaces have the same speed, duplex, and VLAN. What is the most likely cause of the suspended interfaces?
⚠ Common exam trap
Cisco often tests the misconception that all interfaces must match in speed, duplex, and VLAN to form an EtherChannel, but the trap here is that the LACP mode mismatch (active/passive vs. on) is the specific cause of suspended interfaces even when other parameters are consistent.
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
✓
The remote switch interfaces corresponding to the suspended local interfaces are configured with the 'on' mode instead of 'active' or 'passive' for LACP.
LACP requires both ends of a link to be configured in either 'active' or 'passive' mode to negotiate an EtherChannel. If some remote interfaces are set to 'on' mode (static EtherChannel), LACP negotiation fails on those links, causing the corresponding local LACP-enabled interfaces to remain in a suspended state. The local switch detects that LACP PDUs are not received on those interfaces and suspends them to prevent misconfiguration. The other two interfaces with correctly configured remote peers form the EtherChannel successfully.
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 interfaces are in err-disabled state due to a spanning-tree loop.
Why it's wrong here
The 's' flag in the EtherChannel summary output represents a suspended state, which is caused by a failure of LACP/PAgP negotiation, not a spanning-tree loop. Err-disabled is a distinct interface state triggered by error conditions such as loop guard, and would appear as 'err-disabled' in the interface status or as 'D' (down) in the EtherChannel summary, not as 's'. Furthermore, a spanning-tree loop would cause a port to be placed in a blocking state by STP, not suspended in an EtherChannel bundle. Therefore, this option misidentifies the state and the underlying cause.
- ✓
The remote switch interfaces corresponding to the suspended local interfaces are configured with the 'on' mode instead of 'active' or 'passive' for LACP.
Why this is correct
When one switch has LACP active/passive and the other has 'on' (static), LACP negotiation fails, and the ports become suspended. Changing the remote switch to 'active' or 'passive' allows LACP to negotiate and bundle the ports.
- ✗
The port-channel interface is shutdown.
Why it's wrong here
If the port-channel interface were shutdown, all member interfaces would show 'D' (down) or 's' but the port-channel itself would show 'SD' or 'D'. The output shows Po1(SU), meaning the port-channel is up and in use.
- ✗
There is a mismatch in the allowed VLANs on the member interfaces.
Why it's wrong here
A mismatch in the allowed VLANs on member interfaces is unlikely to produce the 's' (suspended) flag in the 'show etherchannel summary' output. Such a mismatch typically causes the VLAN consistency check to fail, resulting in the interfaces being placed in a down ('D') or individual ('I') state, rather than suspended. Additionally, the suspension of LACP member ports occurs specifically when the local side is configured for LACP active/passive and the remote side is set to static 'on', so the protocol cannot negotiate. The scenario confirms the VLAN configuration is identical, ruling this out as the root cause.
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 remote switch interfaces corresponding to the suspended local interfaces are configured with the 'on' mode instead of 'active' or 'passive' for LACP.Correct answer▾
Why this is correct
When one switch has LACP active/passive and the other has 'on' (static), LACP negotiation fails, and the ports become suspended. Changing the remote switch to 'active' or 'passive' allows LACP to negotiate and bundle the ports.
✗The interfaces are in err-disabled state due to a spanning-tree loop.Wrong answer — click to see why▾
Why this is wrong here
The exhibit shows the ports as suspended, not err-disabled. Spanning-tree loops typically cause err-disable, not suspension.
✗The port-channel interface is shutdown.Wrong answer — click to see why▾
Why this is wrong here
The port-channel is up (U), so it is not shutdown.
✗There is a mismatch in the allowed VLANs on the member interfaces.Wrong answer — click to see why▾
Why this is wrong here
The scenario explicitly states that all interfaces are configured with the same VLAN, so this is not the cause.
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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Related to this question
Learn chapter
Configuring Switch Ports for Desktops, VoIP Phones, APs, IoT, and Virtualized Hosts
Key term
Ethernet
Ethernet is a wired networking technology that connects devices like computers, printers, and servers to each other and to the internet using cables.
Key term
EtherChannel
EtherChannel is a technology that bundles multiple physical Ethernet links into a single logical link to increase bandwidth and provide redundancy.
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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.