Spanning Tree

Question 1

Spanning Tree Order of Operation

Answer 1

1. Determine root bridge
2. Select root port
3. Select designated ports
4. Block ports with loops

Question 2

Legacy STP Port States

Answer 2

Disabled
Blocking
Listening
Learning
Forwarding

Question 3

Rapid STP Port States

Answer 3

Discarding
Learning
Forwarding

Question 4

Legacy STP Port Roles

Answer 4

Root
Designated
Blocking

Question 5

Rapid STP Port Roles

Answer 5

Root
Designated
Alternate
Backup

Question 6

Default Hello Timer

Answer 6

2 seconds

Question 7

Default forwarding delay timer

Answer 7

15 seconds

Question 8

Default max age timer

Answer 8

20 seconds

Question 9

Bridge ID format

Answer 9

4 bit bridge priority
12 bit system ID extension taken from VLAN number
48 bit MAC address

Question 10

Path Selection process

Answer 10

1. Bridge with lowest root ID becomes the root
2. Prefer the neighbor with the lowest cost to root
3. Prefer the neighbor with the lowest bridge ID
4. Prefer the lowest sender port ID

Question 11

PVST+ enhancement which enables immediate transition into the forwarding state (designates edge ports under MST)

Answer 11

Portfast

Question 12

PVST+ enhancement which enables switches to maintain backup paths to root

Answer 12

Uplink fast

Question 13

PVST+ enhancement which enables immediate expiration of the Max Age timer in the event of an indirect link failure

Answer 13

BackboneFast

Question 14

STP protection which prevents a port from becoming the root port

Answer 14

Root guard

Question 15

STP protection which error-disables a port if a BPDU is received

Answer 15

BPDU Guard

Question 16

STP protection which prevents a blocked port from transitioning to listening after the Max Age timer has expired

Answer 16

Loop Guard

Question 17

STP protection which blocks BPDUs on an interface (disables STP)

Answer 17

BPDU filter

Question 18

RSTP link type which connects to exactly one other bridge (full duplex)

Answer 18

Point-to-Point

Question 19

RSTP link type which potentially connects to multiple bridges (half duplex)

Answer 19

Shared

Question 20

RSTP link type which connects to a single host; designated by PortFast

Answer 20

Edge

Question 21

Default STP port costs

Answer 21

10Mb - 100
100Mb - 19
1Gb - 4
10Gb - 2
20Gb+ - 1

Question 22

True/False: A switch in MST mode uses default STP port costs

Answer 22

False, switch will use long-path-cost calculation

Question 23

Long-path-cost values

Answer 23

10Mb - 2,000,000
100Mb - 200,000
1Gb - 20,000
10Gb - 2,000
20Gb+ - 200

Question 24

Switch requirements to be in the same MST region

Answer 24

same vlan-to-instance mapping
same configuration revision number
same instance name

Question 25

Maximum number of STP instances in PVST+

Answer 25

128 instances

Question 26

Maximum number of MST instances

Answer 26

65 including instance 0

Question 27

Number of VLANs supported per MST instance

Answer 27

Unlimited