350-401 EtherChannel Practice Test 2 — 15 Questions

Question 1

A network engineer runs the following command on Switch SW7:

SW7# show interfaces port-channel 1
Port-channel1 is up, line protocol is up (connected)
  Hardware is EtherChannel, address is aaaa.bbbb.cccc (bia aaaa.bbbb.cccc)
  Description: Link to Core
  Internet address is 192.168.1.1/30
  MTU 1500 bytes, BW 2000000 Kbit/sec, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, link type is auto, media type is unknown
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 1000 bits/sec, 2 packets/sec
  5 minute output rate 500 bits/sec, 1 packets/sec
     12345 packets input, 1234567 bytes, 0 no buffer
     Received 0 broadcasts (0 IP multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     67890 packets output, 9876543 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out

Based on this output, what can be concluded?

Accepted Answer

The bandwidth of 2 Gbps suggests that two 1 Gbps links are aggregated.. The output shows that Port-channel1 is up with an IP address (192.168.1.1/30), indicating it is a Layer 3 interface. The bandwidth is 2 Gbps (2000000 Kbit/sec), which suggests that two 1 Gbps links are aggregated. The interface has no errors and low utilization. The correct answer is that the port-channel is a Layer 3 interface with an aggregated bandwidth of 2 Gbps.

Answer

The port-channel is a Layer 2 interface because it has an IP address.

Answer

The interface is experiencing input errors due to CRC errors.

Answer

The port-channel is operating at half-duplex.

Question 2

A network engineer runs the following command on Switch SW8:

SW8# show etherchannel 2 detail | include "Port state|Port: Gi|Partner"
Port: Gi0/0
Port state    = Up, In-Bundle
Port: Gi0/1
Port state    = Up, In-Bundle
Port: Gi0/2
Port state    = Down, Not-In-Bundle
Partner information:
Gi0/0: Partner state = bndl
Gi0/1: Partner state = bndl
Gi0/2: Partner state = down

Based on this output, what can be concluded?

Accepted Answer

Gi0/2 is not bundled because the partner is in 'down' state, indicating a physical layer issue.. The filtered output shows that Gi0/0 and Gi0/1 are up and in-bundle, with their partners also in 'bndl' state. Gi0/2 is down and not in-bundle, with its partner also down. This indicates that the physical link on Gi0/2 is down, possibly due to a cable issue or the neighbor port being down. The correct answer is that Gi0/2 is not part of the EtherChannel because the link is down.

Answer

All three ports are bundled and forwarding traffic.

Answer

The EtherChannel is using PAgP because the partner state shows 'bndl'.

Answer

Gi0/2 is in standby mode waiting to become active.

Question 3

A network engineer runs the following command on Switch SW9:

SW9# show etherchannel 4 port-channel
Port-channels in the group:
---------------------------

Port-channel: Po4    (Primary Aggregator)

Age of the Port-channel   = 0d:00h:20m:10s
Logical slot/port   = 16/4          Number of ports = 3
HotStandby port = null
Port state          = Port-channel Ag-Inuse
Protocol            =   LACP

Ports in the Port-channel:

Index   Load     Port     EC state        No of bits
------+------+------+----------------+----------
  0     00      Gi0/0    Active              4
  1     00      Gi0/1    Active              4
  2     00      Gi0/2    Standby            4

Time since last port bundled:    0d:00h:15m:00s    Gi0/1

Based on this output, what can be concluded?

Accepted Answer

The EtherChannel has a maximum bundle size of 2, so Gi0/2 is a hot-standby port.. The output shows that Gi0/0 and Gi0/1 are in 'Active' state, while Gi0/2 is in 'Standby' state. In LACP, a standby port is a hot-standby port that becomes active if an active port fails. This is configured using the 'lacp max-bundle' command or when the number of ports exceeds the maximum allowed. The correct answer is that Gi0/2 is a hot-standby port ready to take over if an active port fails.

Answer

All three ports are actively forwarding traffic in the EtherChannel.

Answer

Gi0/2 is in standby mode because it is not receiving LACP packets from the neighbor.

Answer

The port-channel is not in use because the load is zero.

Question 4

Consider the following configuration snippet:

interface Port-channel1
 switchport mode trunk
 switchport trunk allowed vlan 10,20,30
!
interface GigabitEthernet0/1
 channel-group 1 mode active
!
interface GigabitEthernet0/2
 channel-group 1 mode passive

What is the effect of this configuration?

Accepted Answer

The EtherChannel will form using LACP, and the port-channel will operate as a trunk carrying VLANs 10, 20, and 30.. The configuration creates an EtherChannel using LACP with one side in active mode and the other in passive mode. The active side initiates negotiation, so the channel will form. The port-channel interface is configured as a trunk, so the channel will carry VLANs 10, 20, and 30.

Answer

The EtherChannel will not form because both sides must use the same LACP mode.

Answer

The EtherChannel will form using PAgP because the mode is not specified as lacp.

Answer

The EtherChannel will form but only VLAN 1 will be allowed on the trunk.

Question 5

Given the following configuration:

interface Port-channel1
 no switchport
 ip address 192.168.1.1 255.255.255.0
!
interface GigabitEthernet0/1
 no switchport
 channel-group 1 mode on
!
interface GigabitEthernet0/2
 no switchport
 channel-group 1 mode on

Which statement is true about this EtherChannel?

Accepted Answer

The EtherChannel will form and operate as a Layer 3 routed interface.. The 'mode on' command forces the interface into an EtherChannel without any negotiation protocol (no LACP or PAgP). Both sides must be configured with 'mode on' for the channel to come up. The port-channel is a routed interface (no switchport) with an IP address.

Answer

The EtherChannel will form only if the neighbor also uses LACP active mode.

Answer

The EtherChannel will not form because the interfaces are in no switchport mode.

Answer

The EtherChannel will form but will use PAgP negotiation.

Question 6

Examine the following configuration:

interface Port-channel1
 switchport mode trunk
!
interface GigabitEthernet0/1
 switchport mode trunk
 channel-group 1 mode desirable
!
interface GigabitEthernet0/2
 switchport mode access
 channel-group 1 mode desirable

What is the problem with this configuration?

Accepted Answer

The switchport mode mismatch between Gi0/1 (trunk) and Gi0/2 (access) will prevent the EtherChannel from forming.. EtherChannel requires all member interfaces to have the same switchport mode (all trunk or all access). Here, Gi0/1 is configured as trunk, but Gi0/2 is configured as access. This mismatch will prevent the channel from forming.

Answer

The channel-group mode desirable is incompatible with trunk ports.

Answer

The port-channel interface must also be configured as access to match Gi0/2.

Answer

The EtherChannel will form but only Gi0/1 will be active.

Question 7

Consider this configuration:

interface Port-channel1
 switchport mode trunk
 switchport trunk native vlan 999
!
interface GigabitEthernet0/1
 switchport mode trunk
 switchport trunk native vlan 999
 channel-group 1 mode active
!
interface GigabitEthernet0/2
 switchport mode trunk
 switchport trunk native vlan 999
 channel-group 1 mode active

What is the effect of the 'switchport trunk native vlan 999' command on the EtherChannel?

Accepted Answer

The EtherChannel will use VLAN 999 as the native VLAN, and any untagged frames will be associated with VLAN 999.. The native VLAN is used for untagged traffic on a trunk. Setting it to 999 (an unused VLAN) helps prevent VLAN hopping attacks and ensures that any untagged frames are dropped. The configuration is consistent across all member interfaces and the port-channel, so the channel will form.

Answer

The EtherChannel will drop all untagged frames because the native VLAN is not in the allowed list.

Answer

The EtherChannel will not form because the native VLAN must be the same across all interfaces, which it is.

Answer

The EtherChannel will form but the native VLAN will be ignored on the port-channel.

Question 8

Given the configuration:

interface Port-channel1
 switchport mode trunk
 switchport trunk allowed vlan 10-20
!
interface GigabitEthernet0/1
 switchport mode trunk
 channel-group 1 mode passive
!
interface GigabitEthernet0/2
 switchport mode trunk
 channel-group 1 mode passive

What is missing for this EtherChannel to form with a neighbor that uses LACP active?

Accepted Answer

Nothing is missing; the configuration is valid and the EtherChannel will form with the neighbor.. The configuration uses LACP passive on both member interfaces. For LACP to negotiate, one side must be active. The neighbor is active, so that is fine. However, the port-channel interface does not have the 'switchport trunk allowed vlan' command applied; it is only on the port-channel. That is actually correct—the port-channel configuration applies to the channel. But the question asks what is missing; the answer is that the port-channel interface itself must have the allowed VLAN list, which it does. Actually, the configuration is complete. The trick is that the port-channel interface already has the allowed VLAN list. So nothing is missing. But the options might include a common mistake. Let's re-evaluate: The configuration shows the port-channel with allowed VLANs, and the member ports without. That is correct. So the answer is that nothing is missing. However, a common issue is that the member ports must also have the same allowed VLAN list if configured individually, but here they are not configured, so they inherit from the port-channel. This is fine. So the correct answer is that the configuration is valid.

Answer

The member interfaces must also have the 'switchport trunk allowed vlan 10-20' command.

Answer

The port-channel interface must be configured with 'channel-group 1' to associate the member ports.

Answer

The member interfaces must use LACP active mode to form the channel.

Question 9

Examine the following configuration:

interface Port-channel1
 switchport mode trunk
!
interface GigabitEthernet0/1
 switchport mode trunk
 channel-group 1 mode active
 spanning-tree portfast
!
interface GigabitEthernet0/2
 switchport mode trunk
 channel-group 1 mode active
 spanning-tree portfast

What is the effect of the 'spanning-tree portfast' command on the member interfaces of this EtherChannel?

Accepted Answer

The PortFast on the member interfaces will be ignored because they are part of an EtherChannel.. PortFast is used on access ports to immediately transition to forwarding state, bypassing STP listening/learning. However, on trunk ports, PortFast can cause loops if used incorrectly. In this case, the member interfaces are part of an EtherChannel, and PortFast is applied at the interface level. But the port-channel interface itself does not have PortFast. The PortFast on member interfaces is ignored because the channel is a trunk; the port-channel interface controls STP. The correct practice is to apply PortFast on the port-channel interface, not on individual members.

Answer

The PortFast will be applied to the EtherChannel, causing it to immediately transition to forwarding.

Answer

The PortFast will cause the EtherChannel to form faster.

Answer

The configuration will cause a spanning-tree loop because PortFast is used on trunk ports.

Question 10

What is the default load-balancing method used by Cisco switches for EtherChannel?

Accepted Answer

Source MAC address. Cisco switches default to source MAC address-based load balancing for EtherChannel. This method distributes traffic based on the source MAC address of the frame, which can lead to uneven distribution if traffic patterns are not diverse.

Answer

Destination MAC address

Answer

Source IP address

Answer

Source and destination IP address

Question 11

Which LACP mode must be configured on at least one side of an EtherChannel for the channel to establish?

Accepted Answer

Active. LACP requires at least one side to be in active mode to initiate negotiation. If both sides are passive, the channel will not form because neither side sends LACP packets.

Answer

Passive

Answer

Desirable

Answer

On

Question 12

What is the maximum number of active member links supported in a single EtherChannel on Cisco Catalyst switches?

Accepted Answer

8. Cisco Catalyst switches support up to 8 active member links in a single EtherChannel. Some platforms also support up to 16 links with 8 active and 8 standby using LACP, but the maximum active links is 8.

Answer

4

Answer

16

Answer

32

Question 13

Drag and drop the steps of LACP EtherChannel negotiation and bundle formation into the correct order, from first to last.

Accepted Answer

Exchange LACP system priority to elect active side. LACP first exchanges system priority to determine which side is active, then exchanges port priorities to select which ports bundle, next negotiates the operational key, then forms the bundle by synchronizing parameters, and finally the port channel interface becomes operational. This order follows the LACP state machine as defined in IEEE 802.3ad.

Question 14

Drag and drop the steps of configuring a Layer 2 EtherChannel using PAgP into the correct order, from first to last.

Accepted Answer

Create port-channel interface with interface port-channel command. First, create the port-channel interface globally. Then set the channel-group mode to desirable on the first interface. Next, set the same mode on the second interface. After that, verify the bundle forms using show commands. Finally, assign the port-channel to a VLAN to enable data forwarding. This sequence ensures PAgP negotiation completes before the bundle is used.

Question 15

Drag and drop the steps of troubleshooting a failed EtherChannel bundle into the correct order, from first to last.

Accepted Answer

Verify port-channel interface exists with show running-config. First, verify that the port-channel interface exists. Then check that physical ports are in the same VLAN and have matching configurations. Next, confirm that the channel-group mode is compatible on all ports. After that, inspect LACP or PAgP counters for errors. Finally, check for hardware or cabling issues if all else fails. This systematic approach isolates configuration errors before hardware faults.