350-401 Spanning Tree Protocol Practice Test 2 — 15 Questions

Question 1

A network engineer runs the following command on Switch SW7:

SW7# show spanning-tree vlan 70

VLAN0070
  Spanning tree enabled protocol ieee
  Root ID    Priority    24646
             Address     aabb.cc00.0c00
             Cost        4
             Port        1 (GigabitEthernet0/1)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    32768  (priority 32768 sys-id-ext 70)
             Address     aabb.cc00.0d00
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- ------------------------------
Gi0/1               Root FWD 4         128.1    P2p
Gi0/2               Desg FWD 4         128.2    P2p
Gi0/3               Altn BLK 4         128.3    P2p

Based on this output, which port is the alternate port?

Accepted Answer

GigabitEthernet0/3. The alternate port is the port that provides an alternative path to the root bridge and is placed in blocking state. In the output, Gi0/3 is shown as 'Altn BLK'.

Answer

GigabitEthernet0/1

Answer

GigabitEthernet0/2

Answer

There is no alternate port.

Question 2

A network engineer runs the following command on Switch SW8:

SW8# show spanning-tree vlan 80

VLAN0080
  Spanning tree enabled protocol ieee
  Root ID    Priority    24656
             Address     aabb.cc00.0e00
             Cost        12
             Port        1 (GigabitEthernet0/1)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    32768  (priority 32768 sys-id-ext 80)
             Address     aabb.cc00.0f00
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- ------------------------------
Gi0/1               Root FWD 12        128.1    P2p
Gi0/2               Desg FWD 4         128.2    P2p
Gi0/3               Desg FWD 4         128.3    P2p
Gi0/4               Altn BLK 4         128.4    P2p

Based on this output, what is the cost of the root port?

Accepted Answer

12. The root port is Gi0/1, and its cost is shown as 12 in the interface table.

Answer

4

Answer

8

Answer

16

Question 3

A network engineer runs the following command on Switch SW9:

SW9# show spanning-tree vlan 90

VLAN0090
  Spanning tree enabled protocol ieee
  Root ID    Priority    24666
             Address     aabb.cc00.1000
             This bridge is the root
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    24666  (priority 24576 sys-id-ext 90)
             Address     aabb.cc00.1000
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- ------------------------------
Gi0/1               Desg FWD 4         128.1    P2p
Gi0/2               Desg FWD 4         128.2    P2p
Gi0/3               Desg FWD 4         128.3    P2p
Gi0/4               Desg FWD 4         128.4    P2p

Based on this output, what is the base priority of the root bridge?

Accepted Answer

24576. The root bridge priority is 24666, which includes the system ID extension of 90. The base priority is 24666 - 90 = 24576.

Answer

24666

Answer

32768

Answer

32858

Question 4

interface GigabitEthernet0/1
 spanning-tree portfast
 spanning-tree bpduguard enable
 end

What is the effect of this configuration?

Accepted Answer

The port will immediately transition to forwarding state and will be error-disabled if a BPDU is received.. PortFast and BPDU Guard are enabled on the interface, which immediately transitions the port to forwarding and disables it if a BPDU is received.

Answer

The port will go through normal STP states and will be error-disabled if a BPDU is received.

Answer

The port will immediately transition to forwarding and ignore any BPDUs received.

Answer

The port will remain in blocking state until a BPDU is received.

Question 5

spanning-tree vlan 10 priority 4096

What is the effect of this global configuration command?

Accepted Answer

The switch will have a bridge priority of 4096 for VLAN 10, increasing its chance to become root bridge.. This sets the bridge priority for VLAN 10 to 4096, making the switch more likely to become the root bridge for that VLAN.

Answer

The switch will have a bridge priority of 4096 for all VLANs.

Answer

The switch will become the root bridge for VLAN 10 immediately.

Answer

The switch will have a bridge priority of 4096 for VLAN 10 and all other VLANs will use 32768.

Question 6

interface GigabitEthernet0/2
 spanning-tree link-type point-to-point
 end

What is the effect of this configuration?

Accepted Answer

The port will use RSTP fast transition mechanisms assuming a point-to-point link.. This manually sets the link type to point-to-point, which enables Rapid Spanning Tree (RSTP) fast transitions on that port.

Answer

The port will become a designated port immediately.

Answer

The port will disable STP on that link.

Answer

The port will use shared medium behavior.

Question 7

interface GigabitEthernet0/3
 spanning-tree guard root
 end

What is the effect of this configuration?

Accepted Answer

The port will error-disable if it receives a BPDU that would cause the switch to become a non-root bridge.. Root Guard is enabled on the port, which will error-disable the port if a superior BPDU (indicating a potential root bridge) is received.

Answer

The port will block all BPDUs received from other switches.

Answer

The port will become the root port for the VLAN.

Answer

The port will ignore BPDUs from switches with lower bridge ID.

Question 8

interface GigabitEthernet0/4
 spanning-tree vlan 20 cost 100
 end

What is the effect of this configuration?

Accepted Answer

The port cost for VLAN 20 is set to 100, making it more likely to be selected as root port if lower than other paths.. This sets the STP path cost for VLAN 20 on this interface to 100, influencing the root port selection.

Answer

The port cost for all VLANs is set to 100.

Answer

The port will become a designated port for VLAN 20.

Answer

The port will have a higher priority in the spanning-tree algorithm.

Question 9

spanning-tree mode rapid-pvst

What is the effect of this global configuration command?

Accepted Answer

The switch will use Rapid PVST+ for all VLANs, providing faster convergence than classic STP.. This enables Rapid PVST+ mode, which runs RSTP per VLAN for faster convergence.

Answer

The switch will use MSTP for all VLANs.

Answer

The switch will use classic STP for all VLANs.

Answer

The switch will disable STP on all ports.

Question 10

What is the default STP hello timer value in seconds?

Accepted Answer

2 seconds. The default hello timer in STP is 2 seconds, used to send BPDUs on the root bridge.

Answer

1 second

Answer

5 seconds

Answer

10 seconds

Question 11

Which of the following is true about the STP max age timer?

Accepted Answer

It is the maximum time a switch stores BPDU information before discarding it.. The max age timer determines how long a switch waits before re-evaluating BPDU information if it stops receiving BPDUs from the root bridge.

Answer

It is the time a port spends in the listening state.

Answer

It is the interval between BPDU transmissions.

Answer

It is the time a port waits before transitioning from blocking to listening.

Question 12

What is the default STP port cost for a 10 Gigabit Ethernet interface?

Accepted Answer

2. Using the short path cost method (default), the cost for 10 Gbps is 2.

Answer

1

Answer

4

Answer

19

Question 13

Drag and drop the steps of STP root bridge election and port state transitions into the correct order, from first to last.

Accepted Answer

Elect root bridge using lowest bridge ID. STP first elects a root bridge based on lowest bridge ID. Then each non-root bridge selects one root port (lowest path cost to root). Next, each segment elects a designated port (lowest root path cost, then lowest bridge ID). All other ports become alternate (blocking). Finally, ports transition through blocking, listening, learning, and forwarding states.

Question 14

Drag and drop the steps of Rapid PVST+ convergence process into the correct order, from first to last.

Accepted Answer

Elect root bridge and assign port roles (RP, DP, AP). Rapid PVST+ first elects the root bridge and determines port roles. It then uses synchronization handshakes between bridges to quickly transition ports to forwarding without relying on timers. Edge ports (connected to hosts) immediately transition to forwarding. Finally, the topology change notification propagates to update MAC address tables.

Question 15

Drag and drop the steps of MST region configuration and operation into the correct order, from first to last.

Accepted Answer

Enter MST configuration mode and set region name. MST configuration begins with entering MST mode and defining the region name, revision number, and VLAN-to-instance mapping. After configuration, the switch computes an MD5 digest of the MST configuration to identify region membership. Switches in the same region then run IST (Internal Spanning Tree) and CIST (Common and Internal Spanning Tree) to elect a root bridge for the region. Finally, per-instance spanning trees are calculated within the region.