mediumMultiple Choice
350-401 Practice Question: Runs the following command on Switch SW3: SW3#…
A network engineer runs the following command on Switch SW3:
SW3# show etherchannel summary
Flags: D - down P - 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
Group Port-channel Protocol Ports ------+-------------+-----------+--------------------------------------------- 1 Po1(SU) LACP Gi0/1(P) Gi0/2(P) Gi0/3(D)
Based on this output, what can be concluded?
⚠ Common exam trap
Cisco often tests the misinterpretation of the 'D' flag as 'down' versus 'standby', leading candidates to incorrectly assume a down port is in a standby or backup role, when in fact it is not participating at all.
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 EtherChannel is using LACP protocol.
The output shows the EtherChannel is using LACP as the protocol, as indicated in the 'Protocol' column. The 'SU' flags on Po1 mean the port-channel is Layer 2 (S) and in use (U), confirming it is active. Therefore, option B is correct because LACP is explicitly listed as the protocol for this EtherChannel.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
All three ports are actively participating in the EtherChannel.
Why it's wrong here
The show etherchannel summary output flags each member port with a state code; Gi0/3 is marked with (D), which indicates the port is down, not participating in the bundle. Although the port-channel may have three members configured, only those with (P) or (I) in parentheses are actively forwarding. Since Gi0/3 is down, only two ports are actively participating, so this statement is incorrect.
- ✓
The EtherChannel is using LACP protocol.
Why this is correct
The Protocol column in the output explicitly reads LACP, which stands for Link Aggregation Control Protocol, the IEEE 802.3ad standard for dynamically negotiating EtherChannels. This confirms the channel is formed using LACP rather than static configuration (mode 'on') or Cisco's proprietary PAgP. Additionally, LACP is the only protocol among these that supports the standby state (flag 'H'), reinforcing that this output is from an LACP-based EtherChannel.
- ✗
The EtherChannel is a Layer 3 port-channel.
Why it's wrong here
The flags for the port-channel interface are shown as 'SU', where 'S' means the interface is in Layer 2 switching mode and 'U' means it is up and in use. In contrast, a Layer 3 EtherChannel would display 'RU' (routed, up) because it would be a routed interface with an IP address. Since 'S' indicates switched (Layer 2), this EtherChannel is not a Layer 3 port-channel, making the statement false.
- ✗
Port Gi0/3 is in standby mode.
Why it's wrong here
In LACP EtherChannels, a port in standby mode is indicated by the flag 'H' (hot-standby) in the show etherchannel summary output, meaning the port is fully operational but held in reserve because the active member limit has been reached. The output for Gi0/3 shows 'D', which stands for down, indicating the port is not operational at all—either physically or administratively. Therefore, Gi0/3 cannot be in standby mode; it is simply down, so this option is incorrect.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-401 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 350-401 exam.