EtherChannels and Link Aggregation Protocols

Question 1

What is the primary purpose of an EtherChannel?
A) To increase bandwidth by combining multiple physical links into one logical link
B) To provide redundancy only
C) To encrypt traffic between switches
D) To prioritize traffic based on QoS

Answer 1

Answer: A

Question 2

Which of the following is NOT a valid EtherChannel load-balancing method?
A) Source MAC address
B) Destination MAC address
C) Source and destination port numbers
D) Packet size

Answer 2

Answer: D

Question 3

What is the maximum number of physical interfaces that can be bundled into a single EtherChannel on most Cisco switches?
A) 4
B) 8
C) 16
D) 32

Answer 3

Answer: B

Question 4

Which protocol is Cisco-proprietary and used for EtherChannel negotiation?
A) LACP
B) PAgP
C) STP
D) CDP

Answer 4

Answer: B

Question 5

What is the IEEE standard protocol for link aggregation?
A) PAgP
B) LACP
C) DTP
D) VTP

Answer 5

Answer: B

Question 6

Which mode in PAgP actively attempts to form an EtherChannel?
A) Auto
B) Desirable
C) Passive
D) On

Answer 6

Answer: B

Question 7

Which LACP mode places the port in a passive negotiating state?
A) Active
B) Passive
C) Auto
D) On

Answer 7

Answer: B

Question 8

What happens if one link in an EtherChannel fails?
A) The entire EtherChannel goes down
B) Traffic is redistributed among remaining links
C) The switch stops forwarding all traffic
D) STP recalculates the topology

Answer 8

Answer: B

Question 9

Which command verifies the EtherChannel configuration on a Cisco switch?
A) show etherchannel summary
B) show interface port-channel
C) show running-config
D) All of the above

Answer 9

Answer: D

Question 10

What must match on all physical links in an EtherChannel?
A) Speed, duplex, and VLAN membership
B) IP address and subnet mask
C) STP priority
D) VTP domain name

Answer 10

Answer: A

Question 11

Which of the following is a requirement for LACP to form an EtherChannel?
A) At least one side must be in “active” mode
B) Both sides must be in “on” mode
C) Ports must be in different VLANs
D) Ports must have different speeds

Answer 11

Answer: A

Question 12

What is the default load-balancing method for EtherChannel on Cisco switches?
A) Source MAC address
B) Destination MAC address
C) Source and destination IP
D) Round-robin

Answer 12

Answer: C

Question 13

Which command configures an EtherChannel to use LACP in active mode?
A) channel-group 1 mode active
B) channel-group 1 mode desirable
C) channel-group 1 mode on
D) channel-protocol lacp

Answer 13

Answer: A

Question 14

What is the purpose of the “on” mode in EtherChannel configuration?
A) Enables PAgP negotiation
B) Enables LACP negotiation
C) Forces the interface into an EtherChannel without negotiation
D) Disables EtherChannel

Answer 14

Answer: C

Question 15

Which of the following is a disadvantage of using “on” mode for EtherChannel?
A) It requires PAgP
B) It requires LACP
C) It does not detect misconfigurations
D) It only works with two links

Answer 15

Answer: C

Question 16

What is the correct syntax to assign an IP address to a Port-channel interface?
A) ip address 192.168.1.1 255.255.255.0 under the physical interface
B) ip address 192.168.1.1 255.255.255.0 under the Port-channel interface
C) set ip address 192.168.1.1/24
D) IP addresses cannot be assigned to Port-channel interfaces

Answer 16

Answer: B

Question 17

Which protocol ensures that all links in an EtherChannel are properly synchronized?
A) STP
B) CDP
C) PAgP/LACP
D) VTP

Answer 17

Answer: C

Question 18

What happens if two switches are configured with mismatched EtherChannel negotiation protocols (e.g., PAgP on one side and LACP on the other)?
A) The EtherChannel forms successfully
B) The EtherChannel does not form
C) Only one link is used
D) The switches use STP instead

Answer 18

Answer: B

Question 19

Which command changes the EtherChannel load-balancing method to use source MAC addresses?
A) port-channel load-balance src-mac
B) port-channel load-balance src-ip
C) port-channel load-balance src-dst-mac
D) port-channel load-balance method src-mac

Answer 19

Answer: A

Question 20

What is the minimum number of links required for an EtherChannel?
A) 1
B) 2
C) 4
D) 8

Answer 20

Answer: B

Question 21

Which of the following is a benefit of using LACP over PAgP?
A) LACP is Cisco-proprietary
B) LACP is an open standard
C) LACP works only with two devices
D) LACP does not require matching configurations

Answer 21

Answer: B

Question 22

What is the purpose of the “passive” mode in LACP?
A) It actively sends LACP packets
B) It responds to LACP packets but does not initiate
C) It disables LACP
D) It forces the port into an EtherChannel

Answer 22

Answer: B

Question 23

Which command displays the LACP neighbor information?
A) show lacp neighbor
B) show etherchannel summary
C) show lacp 1 neighbor
D) show lacp sys-id

Answer 23

Answer: C

Question 24

What is the default PAgP mode if not specified?
A) Auto
B) Desirable
C) On
D) Passive

Answer 24

Answer: A

Question 25

Which of the following is true about Layer 3 EtherChannels? A) They require PAgP B) They require LACP C) They are configured on a routed port D) They cannot be used for inter-VLAN routing

Answer 25

Answer: C

Question 26

What command assigns a physical interface to an EtherChannel group? A) channel-group 1 mode desirable B) port-channel 1 C) interface port-channel 1 D) etherchannel group 1

Answer 26

Answer: A

Question 27

Which of the following is NOT a valid EtherChannel hashing input? A) Source IP B) Destination IP C) VLAN ID D) TCP sequence number

Answer 27

Answer: D

Question 28

What happens if one end of an EtherChannel is configured with "desirable" and the other with "auto"? A) The EtherChannel forms B) The EtherChannel does not form C) Only one link is active D) STP blocks the ports

Answer 28

Answer: A

Question 29

Which command enables LACP globally on a switch? A) lacp enable B) channel-protocol lacp C) lacp system-priority 32768 D) LACP is enabled by default

Answer 29

Answer: B

Question 30

What is the LACP system priority used for? A) To elect a root bridge B) To determine which switch controls the EtherChannel C) To set STP priority D) To assign VLAN membership

Answer 30

Answer: B

Question 31

What is the default LACP mode if not specified? A) Active B) Passive C) On D) Auto

Answer 31

Answer: B

Question 32

Which command shows the EtherChannel load-balancing method? A) show etherchannel load-balance B) show port-channel load-balance C) show etherchannel summary D) show etherchannel port-channel

Answer 32

Answer: A

Question 33

What is the range of valid EtherChannel group numbers? A) 1–64 B) 1–128 C) 1–256 D) 1–4096

Answer 33

Answer: D

Question 34

Which of the following is true about PAgP "auto" mode? A) It actively negotiates B) It only responds to PAgP packets C) It forces the port into an EtherChannel D) It disables PAgP

Answer 34

Answer: B

Question 35

What happens if an EtherChannel is misconfigured (e.g., speed mismatch)? A) The port is disabled B) The port remains up but does not join the EtherChannel C) The entire switch reboots D) The port joins the EtherChannel but drops packets

Answer 35

Answer: B

Question 36

Which command configures an EtherChannel to use PAgP in desirable mode? A) channel-group 1 mode desirable B) channel-group 1 mode active C) channel-group 1 mode auto D) pagp channel-group 1 desirable

Answer 36

Answer: A

Question 37

What is the purpose of the "channel-group" command? A) To enable LACP B) To assign an interface to an EtherChannel C) To configure STP D) To set the VLAN membership

Answer 37

Answer: B

Question 38

Which of the following is a disadvantage of static EtherChannel ("on" mode)? A) It requires PAgP B) It does not detect misconfigurations C) It only works with LACP D) It cannot be used with more than two links

Answer 38

Answer: B

Question 39

What is the correct sequence to configure an LACP EtherChannel? A) Create Port-channel → Assign interfaces → Set LACP mode B) Assign interfaces → Set LACP mode → Create Port-channel C) Set LACP mode → Assign interfaces → Create Port-channel D) The order does not matter

Answer 39

Answer: A

Question 40

Which command shows detailed LACP information for an interface? A) show lacp interface GigabitEthernet 0/1 B) show etherchannel interface GigabitEthernet 0/1 C) show pagp interface GigabitEthernet 0/1 D) show interface GigabitEthernet 0/1 lacp

Answer 40

Answer: A

Question 41

What is the LACP port priority used for? A) To elect a root bridge B) To determine which ports are active in an EtherChannel C) To assign VLAN membership D) To set STP priority

Answer 41

Answer: B

Question 42

Which of the following is true about Layer 2 EtherChannels? A) They require an IP address B) They are used between switches C) They cannot carry VLAN traffic D) They only work with PAgP

Answer 42

Answer: B

Question 43

What happens if an EtherChannel bundle has more than eight links? A) Only the first eight are used B) The switch disables the extra links C) The switch uses all available links D) The EtherChannel fails to form

Answer 43

Answer: B

Question 44

Which command configures an EtherChannel to use source and destination IP for load balancing? A) port-channel load-balance src-dst-ip B) port-channel load-balance ip C) port-channel load-balance method src-dst-ip D) etherchannel load-balance src-dst-ip

Answer 44

Answer: A

Question 45

What is the purpose of the "show etherchannel summary" command? A) To display STP information B) To show EtherChannel status and member ports C) To configure LACP D) To enable PAgP

Answer 45

Answer: B

Question 46

Which of the following must be consistent across all EtherChannel member ports? A) IP address B) STP cost C) VLAN configuration D) VTP domain

Answer 46

Answer: C

Question 47

What is the default PAgP mode when using "channel-group 1 mode desirable"? A) Auto B) Desirable C) On D) Passive

Answer 47

Answer: B

Question 48

What happens if two switches are configured with "channel-group mode on" on both sides? A) The EtherChannel forms B) The EtherChannel does not form C) Only one link is active D) STP blocks the ports

Answer 48

Answer: A

Question 49

What is the primary advantage of using EtherChannel over single links? A) Increased bandwidth and redundancy B) Lower latency C) Better encryption D) Simplified STP configuration

Answer 49

Answer: A

Question 50

Which command displays the PAgP neighbor information? A) show pagp neighbor B) show etherchannel neighbor C) show pagp 1 neighbor D) show pagp summary

Answer 50

Answer: C