Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
An EtherChannel uses LACP. One side is configured correctly, but the peer side has a different switchport mode on one of the member links. What is the most likely result?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
The bundle may fail to form correctly because the member-link settings are inconsistent.
This is correct because EtherChannel depends on compatible member settings.
B
Distractor review
The switch automatically rewrites the peer configuration to match.
This is wrong because the switch does not self-correct the peer in that way.
C
Distractor review
LACP converts the mismatched link into a routed interface automatically.
This is wrong because LACP does not create routed ports automatically.
D
Distractor review
The VLAN becomes the root bridge.
This is wrong because EtherChannel mismatch does not cause VLAN root election in that way.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is believing that LACP automatically fixes configuration mismatches on the peer side, such as differing switchport modes. Candidates may incorrectly assume that enabling LACP alone guarantees EtherChannel formation regardless of member link settings. This misconception leads to selecting answers suggesting automatic rewriting of peer configurations or conversion of mismatched links into routed interfaces. In reality, LACP only negotiates link aggregation parameters and requires consistent configurations on both ends. Misconfigured member links cause the bundle to fail or form partially, which can be subtle and confusing during troubleshooting.
Technical deep dive
How to think about this question
EtherChannel is a technology that aggregates multiple physical Ethernet links into a single logical link to increase bandwidth and provide redundancy. Link Aggregation Control Protocol (LACP) is a dynamic protocol used to negotiate and maintain EtherChannel bundles between switches. For EtherChannel to function correctly, all member links must have consistent configurations, including switchport mode, VLAN membership, speed, duplex, and trunking settings. LACP helps identify compatible links but does not override configuration mismatches. When one side of an EtherChannel is configured correctly with LACP but the peer side has a different switchport mode on one member link, the bundle formation fails or is incomplete. This is because EtherChannel requires all member links to have matching operational parameters to bundle them successfully. LACP packets are exchanged to verify compatibility, but if the switchport modes differ (for example, one side is access and the other is trunk), the protocol will not aggregate that link, causing the bundle to be partial or fail. A common exam trap is assuming that LACP automatically corrects or rewrites the peer’s configuration or that mismatched links convert to routed interfaces. In reality, LACP only negotiates link aggregation parameters and does not modify switchport modes or VLAN settings. Misconfigured member links cause EtherChannel to fail silently or partially, leading to inconsistent forwarding behavior and potential network issues. Understanding this helps troubleshoot EtherChannel problems and ensures consistent configuration across all member links.
KKey Concepts to Remember
- EtherChannel aggregates multiple physical Ethernet links into a single logical link to increase bandwidth and provide redundancy.
- LACP dynamically negotiates and maintains EtherChannel bundles but requires consistent member link configurations to form correctly.
- All member links in an EtherChannel must have matching switchport modes, VLAN settings, speed, and duplex for successful bundle formation.
- LACP does not automatically correct or rewrite mismatched switchport modes on the peer side of an EtherChannel.
- If member link configurations differ, the EtherChannel bundle may fail to form or form partially, causing inconsistent network behavior.
- Switchport mode mismatches between EtherChannel peers prevent proper LACP negotiation and link aggregation.
- EtherChannel failure due to configuration mismatch does not trigger VLAN root bridge election or convert links to routed interfaces.
- Troubleshooting EtherChannel requires verifying that all member links have identical operational parameters on both ends.
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
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?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
EtherChannel aggregates multiple physical Ethernet links into a single logical link to increase bandwidth and provide redundancy.
What is the correct answer to this question?
The correct answer is: The bundle may fail to form correctly because the member-link settings are inconsistent. — The most likely result is that the bundle will not form cleanly because EtherChannel requires member links to agree on important operational settings. In practical terms, LACP negotiation alone is not enough. The links also need compatible characteristics such as switchport mode, VLAN handling, speed, and duplex where relevant. This is a common troubleshooting pattern. It tests whether you know that bundle membership depends on configuration consistency, not just on enabling LACP.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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