Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Exhibit
SW1: interface range g1/0/1-2 channel-group 5 mode active SW2: interface range g1/0/1-2 channel-group 5 mode on
Two switches are supposed to form an EtherChannel, but the bundle never comes up. Which explanation best matches the exhibit?
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
Distractor review
The switches are using different native VLANs.
That may cause trunk issues, but it does not explain this specific EtherChannel mode mismatch.
B
Best answer
LACP active on one side is incompatible with mode on on the other side.
That is exactly why the channel does not negotiate properly.
C
Distractor review
Both sides must use PAgP desirable mode.
PAgP is optional, not required.
D
Distractor review
The interfaces must be configured as routed ports first.
EtherChannel commonly bundles switch ports or trunks.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is assuming that static mode 'on' can form an EtherChannel with any dynamic mode like LACP active. Static mode 'on' disables negotiation, so if the other side uses LACP active, it waits for negotiation that never happens, causing the bundle to fail. Another trap is confusing native VLAN mismatches with EtherChannel formation issues; while native VLAN mismatches cause trunk problems, they do not prevent EtherChannel negotiation. Candidates may also incorrectly believe PAgP modes must both be 'desirable' to form a channel, but PAgP supports 'auto' and 'desirable' modes for negotiation. Understanding these distinctions prevents misdiagnosis of EtherChannel failures.
Technical deep dive
How to think about this question
EtherChannel technology allows multiple physical Ethernet links to be combined into one logical link, increasing bandwidth and providing redundancy between switches. Cisco supports three modes for EtherChannel formation: static mode 'on', LACP (Link Aggregation Control Protocol), and PAgP (Port Aggregation Protocol). LACP and PAgP are negotiation protocols that dynamically form the channel, while static mode 'on' forces the channel without negotiation. LACP is an IEEE standard and supports active and passive modes, where active mode actively initiates negotiation and passive mode responds to negotiation requests. For EtherChannel to form successfully, both ends must use compatible protocols and modes. If one side is configured with LACP active mode, it expects the other side to be either LACP active or passive to negotiate the channel. If the other side uses static mode 'on', it does not participate in negotiation, causing the channel formation to fail. Similarly, PAgP modes must match on both sides for negotiation. Native VLAN mismatches or routed port configurations do not directly prevent EtherChannel formation but can cause other connectivity issues. The exam trap here is confusing negotiation protocols and modes. Candidates often assume that any mode combination will form an EtherChannel, but mismatched protocols or static versus dynamic modes cause failure. Practically, network engineers must ensure both sides use the same EtherChannel protocol and compatible modes to avoid link bundling issues. This understanding is crucial for troubleshooting EtherChannel problems in Cisco networks and for passing the CCNA exam.
KKey Concepts to Remember
- EtherChannel bundles multiple physical switch ports into a single logical link to increase bandwidth and provide redundancy.
- LACP (Link Aggregation Control Protocol) requires both ends to be configured in compatible modes: either active or passive for negotiation.
- Static EtherChannel mode 'on' forces the channel without negotiation and requires the other side to also use static mode 'on'.
- PAgP (Port Aggregation Protocol) uses modes 'desirable' and 'auto' and is Cisco-proprietary, but is not mandatory for EtherChannel formation.
- Native VLAN mismatches can cause trunking issues but do not prevent EtherChannel negotiation or formation directly.
- EtherChannel does not support bundling routed ports; it only bundles switchports configured as access or trunk interfaces.
- A mismatch between LACP active mode and static mode 'on' causes the EtherChannel bundle to fail to form due to incompatible negotiation methods.
- Correct EtherChannel formation depends on matching protocols and modes on both sides to ensure proper negotiation and link bundling.
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 bundles multiple physical switch ports into a single logical link to increase bandwidth and provide redundancy.
What is the correct answer to this question?
The correct answer is: LACP active on one side is incompatible with mode on on the other side. — One side is using LACP active mode and the other side is forcing a static channel-group with mode on. Those modes are not compatible. LACP needs active or passive on both sides, while PAgP uses desirable or auto, and static mode on expects a manual bundle on the other side.
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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