The answer is that interface Gi0/2 is in stand-alone mode because it is not receiving PAgP packets from the neighbor. In PAgP stand-alone mode, indicated by the (I) flag in the show etherchannel summary output, a port is not bundled into the port-channel and instead operates as a regular Layer 3 interface, typically because the neighboring switch port is not configured for PAgP or there is a protocol mismatch. On the ENCOR 350-401 exam, this scenario tests your ability to read EtherChannel flags and understand that PAgP requires both ends to negotiate; a common trap is confusing the (I) flag with a suspended or down state. Remember that (P) means bundled, (I) means isolated—think “I for Independent” to recall that the port stands alone without PAgP negotiation.
350-401 EtherChannel Practice Question
This 350-401 practice question tests your understanding of etherchannel. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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.
A network engineer runs the following command on Switch SW6:
SW6# show etherchannel 3 summary
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use N - not in use, no aggregation
f - failed to allocate aggregator
M - not in use, minimum links not met
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
Number of channel-groups in use: 1
Number of aggregators: 1
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Interface Gi0/2 is in stand-alone mode because it is not receiving PAgP packets from the neighbor.
The output shows that Port-channel3 is a Layer 3 (R) port-channel in use (U) using PAgP. Two ports (Gi0/0 and Gi0/1) are bundled (P), while Gi0/2 is in stand-alone mode (I). Stand-alone mode in PAgP means the port is not part of the channel, typically because the neighbor is not configured for PAgP or there is a mismatch. The correct answer is that Gi0/2 is not bundled and is operating as a regular interface.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Port-channel 3 is a Layer 2 EtherChannel.
Why it's wrong here
The 'R' flag indicates Layer 3, not Layer 2.
✓
Interface Gi0/2 is in stand-alone mode because it is not receiving PAgP packets from the neighbor.
Why this is correct
The 'I' flag means stand-alone, typically due to PAgP negotiation failure.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
All three interfaces are bundled and forwarding traffic.
Why it's wrong here
Gi0/2 is stand-alone, so only two ports are bundled.
✗
The EtherChannel is not in use because the 'U' flag is missing.
Why it's wrong here
The 'U' flag is present in Po3(RU), indicating it is in use.
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 question in full detail.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 350-401 OSPF questions on adjacency and route selection.
EtherChannel — This question tests EtherChannel — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: Interface Gi0/2 is in stand-alone mode because it is not receiving PAgP packets from the neighbor. — The output shows that Port-channel3 is a Layer 3 (R) port-channel in use (U) using PAgP. Two ports (Gi0/0 and Gi0/1) are bundled (P), while Gi0/2 is in stand-alone mode (I). Stand-alone mode in PAgP means the port is not part of the channel, typically because the neighbor is not configured for PAgP or there is a mismatch. The correct answer is that Gi0/2 is not bundled and is operating as a regular interface.
What should I do if I get this 350-401 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 350-401 OSPF questions on adjacency and route selection.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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