Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Exhibit
interface GigabitEthernet0/1 switchport mode trunk channel-group 1 mode active interface GigabitEthernet0/2 switchport mode access channel-group 1 mode active
Based on the exhibit, what is the most likely reason the port-channel is not forming as expected?
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 member links use different switchport modes, so the channel cannot form correctly.
This is correct because trunk/access inconsistency breaks EtherChannel compatibility.
B
Distractor review
LACP requires both interfaces to use different channel-group numbers.
This is wrong because member interfaces in the same bundle use the same channel-group number.
C
Distractor review
The interfaces must both be configured for PPP.
This is wrong because PPP is unrelated to switch EtherChannel configuration.
D
Distractor review
The bundle fails because BGP is not enabled on the switch.
This is wrong because EtherChannel does not depend on BGP.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is to mistakenly believe that enabling routing protocols such as BGP or configuring PPP on interfaces affects EtherChannel formation. Candidates may also incorrectly assume that LACP requires different channel-group numbers on member interfaces. These misconceptions distract from the real issue: inconsistent switchport modes between member links. The exam tests your understanding that all member interfaces must share the same switchport mode (trunk or access) for the port-channel to form. Overlooking this fundamental requirement leads to selecting incorrect answers that mention unrelated protocols or configuration details.
Technical deep dive
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.
Related practice questions
Related 200-301 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
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 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?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
Discussion
Loading comments…
Sign in to join the discussion.