Practise CCNA 200-301 v2 practice questions — original exam-style scenarios covering every exam domain, with detailed explanations, wrong-answer analysis, and common exam traps.
EtherChannel bundles multiple physical links into a single logical port-channel. The CCNA tests LACP vs PAgP vs static EtherChannel, the mode combinations that form a channel, and common configuration errors. These appear as configuration tasks and troubleshooting scenarios.
Quick answer
EtherChannel questions usually test whether bundled links have matching settings and whether LACP, PAgP or static mode is being used correctly.
LACP, PAgP and static EtherChannel modes.
Matching speed, duplex, VLAN, trunk and native VLAN settings.
Port-channel interface behaviour.
Why a link fails to join an EtherChannel bundle.
Related practice questions
Related 200-301 topic practice pages
Scenario questions usually connect to one or more exam topics. Use these links to review the underlying concepts behind the scenario.
A network engineer configures an EtherChannel between two Cisco switches SW1 and SW2 using LACP. After configuration, hosts connected to SW1 report intermittent connectivity to hosts on SW2. The engineer checks the EtherChannel status and sees that the trunk is up but only allows VLAN 1, while the hosts communicate across VLANs 10 and 20. Which command should the engineer apply to both switches to resolve the issue?
Network Topology
A
channel-group 1 mode active
Why wrong: The ports are already in LACP active mode (as shown by the protocol being LACP and the ports being bundled). Reapplying this command will not fix the intermittent connectivity.
B
switchport trunk allowed vlan 1,10,20
This command ensures that all member ports of the EtherChannel have the same VLAN list. Inconsistent allowed VLANs across member ports can cause traffic to be dropped intermittently. Applying this to all member interfaces on both switches resolves the issue.
C
lacp rate fast
Why wrong: This command changes the LACP rate to fast, which sends LACP packets every second instead of every 30 seconds. This would not cause intermittent connectivity; it is used for faster failure detection.
D
switchport mode trunk
Why wrong: The ports are already configured as trunk ports (the Po1 is Layer2 and trunking is implied). Reapplying this command will not resolve the intermittent connectivity.
Drag and drop the following steps into the correct order to configure an LACP EtherChannel on two Cisco switches using active mode.
A
Enter interface configuration mode for the physical ports (interface range gigabitethernet 0/1-2).
Before assigning any channel-group properties, you must enter the config-if context for the interfaces that will participate in the EtherChannel.
B
Configure the channel-group for the interfaces using mode active (channel-group 1 mode active).
The channel-group command with the active mode enables LACP negotiation, which is essential for a dynamic EtherChannel using the LACP protocol.
C
Optionally configure the Port-Channel interface (for example, switchport mode trunk).
After binding the physical ports to a channel group, applying desired Layer 2 settings to the logical Port-Channel interface ensures consistency across the bundle.
D
Verify the EtherChannel status with the show etherchannel summary command.
Verification confirms the EtherChannel is formed, lists member ports, and shows the protocol in use (LACP), completing the configuration process.
A network engineer checks EtherChannel status on a switch and sees the following output:
Group Port-channel Protocol Ports
------+-------------+---------+-----------------------------
1 Po1(SD) LACP Gi1/0/1(s) Gi1/0/2(I)
What is the most likely reason the EtherChannel is not forwarding traffic?
A
The member interfaces have mismatched speed or duplex settings
Why wrong: Speed or duplex mismatches can definitely break an EtherChannel, which makes this option tempting. The problem is that the exhibit does not specifically prove that speed or duplex is the issue. It only proves that the links are not bundling correctly. On exam-style questions, choose the conclusion directly supported by the output before jumping to one of several possible hidden causes.
B
The port channel is Layer 3 instead of Layer 2
Why wrong: A Layer 3 port-channel can work perfectly well when intentionally configured that way, so the phrase 'Layer 3' does not explain the failure on its own. The real problem shown here is that the member interfaces are not joining the logical channel correctly. The status flags point to a bundle formation problem, not simply to the channel being Layer 3 or Layer 2.
C
At least one member interface is not bundled correctly, so the logical channel is down
Correct. This is correct. The logical EtherChannel is down because the physical members are not properly bundled. The status display is telling you that the switch did not build a working aggregated link, so the port-channel cannot carry traffic as intended.
D
LACP requires exactly four links to form a bundle
Why wrong: LACP does not require four links. Two-link EtherChannels are extremely common, and LACP can negotiate bundles with fewer than four member interfaces. The issue is not link count. The issue is that the displayed interfaces are not in a healthy bundled state.
The port-channel interface 1 does not exist. Configure a LACP EtherChannel between SW1 and SW2 using these two interfaces, with port-channel 1 and mode active on both sides. Ensure the channel forms by resolving any speed/duplex or VLAN mismatches. After configuration, verify with 'show etherchannel summary'.
The EtherChannel will not form because the physical interfaces have mismatched speed/duplex and VLAN assignments. You must configure both interfaces with the same speed (1000), duplex (full), and access VLAN (10), then apply channel-group 1 mode active on each.
This is correct because LACP requires all member interfaces to have identical speed, duplex, and VLAN configuration. Mismatches cause the channel to fail. The fix is to unify these parameters and then set channel-group mode active on both interfaces.
B
The EtherChannel will form successfully because LACP active mode negotiates the channel regardless of speed/duplex or VLAN differences.
Why wrong: This is incorrect because LACP does not override speed/duplex or VLAN mismatches; these must match on all member interfaces for the channel to form.
C
The EtherChannel will not form because the port-channel interface must be configured with the same VLAN as the physical interfaces, but the physical interfaces can have different speeds.
Why wrong: This is incorrect because speed must match on all physical interfaces; different speeds prevent the channel from forming.
D
The EtherChannel will form successfully because the port-channel interface inherits the VLAN from the first physical interface added, so no additional configuration is needed.
Why wrong: This is incorrect because the port-channel interface does not automatically inherit VLAN settings; it must be explicitly configured, and all physical interfaces must have matching VLANs.
An administrator configures an EtherChannel between SW1 and SW2. The port-channel interfaces are physically up, but the EtherChannel bundle fails to come up. On SW1, the channel-group is set to mode active; on SW2, it is set to mode on. What is the most likely cause?
Exhibit
SW1# show etherchannel summary
Group Port-channel Protocol Ports
1 Po1(SD) LACP Gi1/0/1(I) Gi1/0/2(I)
SW1 interface range gi1/0/1-2
channel-group 1 mode active
SW2 interface range gi1/0/1-2
channel-group 1 mode on
A
The switch priority values are mismatched
Why wrong: Priority can affect STP, not whether LACP negotiates with mode on.
B
One side is using LACP active while the other side is set to on
Mode on does not negotiate LACP.
C
The native VLAN must be VLAN 1 for EtherChannel to form
Why wrong: That is not a requirement.
D
Gi1/0/2 cannot be bundled because interfaces must be in different VLANs
Why wrong: Bundled links must be configured consistently, not differently.
A network engineer is configuring an EtherChannel between two switches. After applying the configuration, the port-channel fails to form. What is the most likely reason?
Exhibit
interface GigabitEthernet0/1
switchport mode trunk
channel-group 1 mode active
interface GigabitEthernet0/2
switchport mode access
channel-group 1 mode active
A
The member links use different switchport modes, so the channel cannot form correctly.
This is correct because trunk/access inconsistency breaks EtherChannel compatibility.
B
LACP requires both interfaces to use different channel-group numbers.
Why wrong: This is wrong because member interfaces in the same bundle use the same channel-group number.
C
The interfaces must both be configured for PPP.
Why wrong: This is wrong because PPP is unrelated to switch EtherChannel configuration.
D
The bundle fails because BGP is not enabled on the switch.
Why wrong: This is wrong because EtherChannel does not depend on BGP.
A two-switch EtherChannel bundle is configured with LACP. One side uses active mode on both member links, while the other side uses passive mode on both member links. What is the result?
A
The bundle forms successfully
Correct choice.
B
The links remain individual because both sides must use active
A network administrator is configuring a Layer 2 EtherChannel between two switches. Switch A uses 'channel-group 1 mode active', and Switch B uses 'channel-group 1 mode desirable'. All member interfaces are trunk ports with identical allowed VLANs. The EtherChannel fails to form. What is the most likely cause?
Exhibit
SW1:
interface range g1/0/1-2
switchport mode trunk
channel-group 5 mode active
SW2:
interface range g1/0/1-2
switchport mode trunk
channel-group 5 mode desirable
A
The switches are using different EtherChannel negotiation protocols.
LACP active cannot form a channel with PAgP desirable.
You are connected to SW1 via the console. SW1 is a Layer 2 switch with two links to SW2: G0/1 and G0/2. The administrator wants to combine these two links into an EtherChannel using LACP. Configure an EtherChannel on SW1 for these ports and verify.
A
interface range g0/1-2
channel-group 1 mode active
This configuration enables LACP active mode on both ports, which initiates negotiation with the neighbor to form an EtherChannel. The 'channel-group 1 mode active' command is correct for LACP.
B
interface range g0/1-2
channel-group 1 mode desirable
Why wrong: This is incorrect because 'mode desirable' is a PAgP (Cisco proprietary) parameter, not LACP. The question specifies LACP, so this command would use PAgP instead.
Why wrong: This is incorrect because both ports must use the same LACP mode to form a channel. Mixing 'active' and 'passive' on the same switch will not work; LACP requires consistent mode on both ends.
D
interface port-channel 1
channel-group 1 mode active
Why wrong: This is incorrect because the 'channel-group' command is applied on physical interfaces, not on the port-channel interface. The port-channel interface is created automatically after the channel-group command is applied to physical ports.
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