7 - Switches

Question 1

What protocol is used to prevent loops on a switch?

Answer 1

STP or spanning tree protocol

Question 2

What are the names of the led lights on a switch?

Answer 2

Syst or system
rps or redundant power system
stat or port status
duplx or duplex
speed

Question 3

What are the switching modes?

Answer 3

store and forward switching
cut through switching
adaptive cut through switching
fragment free switching

Question 4

What switching mode receives the entire frame before forwarding the frame? It also verify that no CRC errors are present.

Answer 4

Store and forward switching mode

Question 5

What switching mode begins forwarding a frame after the first six bytes forwarding the frame before its fully received?

Answer 5

cut through switching mode

Question 6

What switching mode provides a balance between store and forward switching and cut through switching?

Answer 6

adaptive cut through switching mode

Question 7

What switching mode has to receive 64 bytes of the frame before deciding whether to forward the frame?

Answer 7

fragment free switching mode

Question 8

What standard allows compliant devices to automatically communicate port speed and duplex over a 10Mb or 100Mb connection?

Answer 8

IEEE 802.3u

Question 9

What standard allows compliant devices to automatically communicate port speed and duplex over a 1000Mb connection?

Answer 9

IEEE 802.3z

Question 10

What is displayed in the show interfaces command?

Answer 10

status of interfaces
ip addresses
interface speeds
number of packets sent and received
error counts

Question 11

What is a cause of excessive noise?

Answer 11

usually a physical media problem, bad cable

Question 12

How do you detect excessive noise errors?

Answer 12

show interfaces:
high number of CRC errors
low number of collisions

Question 13

What is a cause of too many collisions?

Answer 13

too many nodes on a segment
bad nic
duplex mismatch

Question 14

How do you detect collision errors?

Answer 14

show interfaces:

high number of collisions

Question 15

What is a symptom of late collision errors?

Answer 15

duplex mismatch

network segment is too long

Question 16

How do you detect late collision errors?

Answer 16

show interfaces:

high number of late collisions

Question 17

What is a symptom of duplex mismatch errors?

Answer 17

intermittent connectivity

performance problems

Question 18

How do you detect duplex mismatch errors?

Answer 18

show interfaces:
high number of collisions
high number of late collisions

Question 19

What is a symptom of speed mismatch errors?

Answer 19

prevents the interface from sending traffic

Question 20

How do you detect speed mismatch errors?

Answer 20

show interfaces status:
check the speed setting
also the interface is usually down

Question 21

What is a symptom of a broadcast storm?

Answer 21

network slowness
cpu utilization is high on switch and computers
loop in the network

Question 22

How do you view the cpu usage on a switch?

Answer 22

show processes command

Question 23

How do you detect broadcast storm errors?

Answer 23

show interfaces:
high collision count
show processes:
high cpu usage 80 - 100%

Question 24

What methods can be used to secure a switch?

Answer 24

disable unused ports

configure port security

Question 25

What is the default mac address count when port security is enabled?

Answer 25

one mac address

Question 26

Where are the mac addresses stored when the sticky keyword is used in switchport port-security mac-address sticky?

Answer 26

in the running config, they will be lost unless the config is writ memed

Question 27

What are the three keywords available for switchport port-security violation command?

Answer 27

``` restrict protect shutdown (default) ```

Question 28

What does the restrict keyword do in switchport port-security violation restrict?

Answer 28

configures the switch to drop traffic from any mac that is not allowed, create a log entry documenting the violation

Question 29

What does the protect keyword do in switchport port-security violation protect?

Answer 29

configures the switch to drop traffic from any mac that is not allowed, does not create a log entry documenting the violation

Question 30

What is the command to configure automatic error-disabled recovery?

Answer 30

errdisable recovery interval 100

Question 31

What command can be used to view port-security configuration?

Answer 31

show port-security

Question 32

What standard is STP based off of?

Answer 32

IEEE 802.1D

Question 33

What layer of the OSI model does spanning tree operate on?

Answer 33

layer 2

Question 34

What are the states of STP?

Answer 34

forwarding | blocking

Question 35

What is PortFast in STP?

Answer 35

feature that provides immediate access to the network for edge ports

Question 36

What are the global configuration commands for portfast?

Answer 36

spanning-tree portfast | spanning-tree portfast interface fa0/1

Question 37

What is BPDU Guard?

Answer 37

used to disable ports that erroneously receive BPDUs.

Question 38

Where should BPDU guard be used?

Answer 38

on edge ports that have portfast enabled

Question 39

What is loop guard?

Answer 39

feature that prevents nondesignated ports from inadvertently forming bridging loops if the steady flow of BPDUs is interrupted

Question 40

What is the global configuration command for loop guard?

Answer 40

spanning-tree loopgaurd default

Question 41

What is the interface command for loop guard?

Answer 41

spanning-tree guard loop

Question 42

What is root guard?

Answer 42

is used to prevent newly introduced switches from being elected as the new root switch

Question 43

What is the global configuration command for root guard?

Answer 43

None, it is only configured on the interface

Question 44

What is the interface command for root guard?

Answer 44

spanning-tree guard root

Question 45

What happens when root guard is enabled on port that has loop guard enabled?

Answer 45

loop guard will be disabled