Module 5: STP Concepts

5.1.10, 5.2.12, 5.3.6 và 5.4.2.

Which statement describes STP?

A. STP is a Layer 2 routing protocol.
B. STP is a Layer 3 routing protocol for Ethernet LANs.
C. STP is a Layer 2 loop prevention protocol for Ethernet LANs.
D. STP is a Layer 3 loop prevention protocol for IP networks.

C. STP is a Layer 2 loop prevention protocol for Ethernet LANs.

Without STP on the Ethernet LAN, which three types of frames could cause a catastrophic loop in the network? (Choose three.)

A. Unicast
B. Unknown unicast
C. Multicast
D. Broadcast

B. Unknown unicast
C. Multicast
D. Broadcast

What device is elected by the Spanning Tree Algorithm? All other switches determine a single least-cost path to this device.

A. root bridge
B. dedicated bridge
C. default gateway
D. core switch

A. root bridge

By default (without any configuration on a switch), what will determine which switch is the root bridge?

A. The bridge priority
B. The extended system ID
C. The MAC address of the switch
D. The bridge ID

C. The MAC address of the switch

The root bridge will be the switch with the:

A. Lowest bridge ID
B. Highest bridge ID
C. Lowest port priority
D. Highest port priority

A. Lowest bridge ID

The port closest to the root bridge in terms of least overall cost (best path) to the root bridge is the:

A. Designated port
B. Blocked port or non-designated port
C. Root port
D. Routed Port

C. Root port

The port on the segment (with two switches) that has the lowest path cost to the root bridge is the:

A. Designated port
B. Blocked port or non-designated port
C. Root port
D. Routed Port

A. Designated port

Which of the following ports will forward Ethernet frames? (Choose two.)

A. Designated port
B. Blocked port or non-dedicated port
C. Root port

A. Designated port
C. Root port

The sum of individual port costs along the path from the switch to the root bridge is known as the:

A. Least cost path
B. Shortest path cost
C. Best path cost
D. Root path cost

D. Root path cost

How often does a switch send a BPDU?

A. Every 2 seconds
B. Every 15 seconds
C. Every 20 seconds
D. Only when there is a change in the topology

A. Every 2 seconds

Which three STP port states are merged into the RSTP discarding port state? (Choose three.)

A. disabled
B. blocking
C. listening
D. learning
E. forwarding

A. disabled
B. blocking
C. listening

Which protocol was designed to bring faster convergence to STP?

A. PortFast
B. RSTP
C. PVST
D. MSTP

B. RSTP

Which technology solves the problem of a device being unable to get an IPv4 address from a DHCP server due to STP forwarding delay timers?

A. PortFast
B. BPUD guard
C. PVST
D. MSTP

A. PortFast

Which port state will switch ports immediately transition to when configured for PortFast?

A. forwarding
B. blocking
C. listening
D. learning

A. forwarding

After the election of the root bridge has been completed, how will switches find the best paths to the root bridge?

A. Each switch will analyze the port states of all neighbors and use the designated ports to forward traffic to the root.
B. Each switch will analyze the sum of all port costs to reach the root and use the path with the lowest cost.
C. Each switch will analyze the sum of the hops to reach the root and use the path with the fewest hops.
D. Each switch will analyze the BID of all neighbors to reach the root and use the path through the lowest BID neighbors.

B. Each switch will analyze the sum of all port costs to reach the root and use the path with the lowest cost.

Which is the default STP operation mode on Cisco Catalyst switches?

A. MST
B. PVST+
C. Rapid PVST+
D. MSTP
E. RSTP

B. PVST+

What value determines the root bridge when all switches connected by trunk links have default STP configurations?

A. VLAN ID
B. MAC address
C. extended system ID
D. bridge priority

B. MAC address

During the implementation of Spanning Tree Protocol, all switches are rebooted by the network administrator. What is the first step of the spanning-tree election process?

A. All the switches send out BPDUs advertising themselves as the root bridge.
B. Each switch determines the best path to forward traffic.
C. Each switch determines what port to block to prevent a loop from occurring.
D. Each switch with a lower root ID than its neighbor will not send BPDUs.

A. All the switches send out BPDUs advertising themselves as the root bridge.

Which two concepts relate to a switch port that is intended to have only end devices attached and intended never to be used to connect to another switch? (Choose two.)

A. bridge ID
B. PortFast
C. edge port
D. extended system ID
E. PVST+

B. PortFast
C. edge port

Which three port states are used by Rapid PVST+? (Choose three.)

A. listening
B. blocking
C. trunking
D. learning
E. forwarding
F. discarding

D. learning
E. forwarding
F. discarding

When PVST is running over a switched network, which port state can participate in BPDU frame forwarding based on BPDUs received, but does not forward data frames?

A. disabled
B. forwarding
C. listening
D. blocking

C. listening

Which STP port role is adopted by a switch port if there is no other port with a lower cost to the root bridge?

A. designated port
B. alternate
C. disabled port
D. root port

D. root port

Which two statements describe a switch port that is configured with PortFast? (Choose two.)

A. The switch port immediately transitions from the listening to the forwarding state.
B. The switch port immediately transitions from blocking to the forwarding state.
C. The switch port sends DHCP requests before transitioning to the forwarding state.
D. The switch port immediately processes any BPDUs before transitioning to the forwarding state.
E. The switch port should never receive BPDUs.

B. The switch port immediately transitions from blocking to the forwarding state.
E. The switch port should never receive BPDUs.

What is one way to correct a spanning tree failure?

A. Replace the cables on failed STP links.
B. Manually remove redundant links in the switched network.
C. Insert redundant links to replace the failed STP links.
D. Replace all instances of STP with RSTP.

B. Manually remove redundant links in the switched network.

What additional information is contained in the 12-bit extended system ID of a BPDU?

A. port ID
B. MAC address
C. IP address
D. VLAN ID

D. VLAN ID

An administrator is troubleshooting a switch and wants to verify if it is a root bridge. What command can be used to do this?

A. show spanning-tree
B. show running-config
C. show vlan
D. show startup-config

A. show spanning-tree

What is an accurate description of redundancy?

A. designing a network to use multiple virtual devices to ensure that all traffic uses the best path through the internetwork
B. configuring a router with a complete MAC address database to ensure that all frames can be forwarded to the correct destination
C. designing a network to use multiple paths between switches to ensure there is no single point of failure
D. configuring a switch with proper security to ensure that all traffic forwarded through an interface is filtered

C. designing a network to use multiple paths between switches to ensure there is no single point of failure

Which three components are combined to form a bridge ID? (Choose three.)

A. Bridge priority
B. Cost
C. Extended system ID
D. IP address
E. MAC address
F. Port ID

A. Bridge priority
C. Extended system ID
E. MAC address

What is an advantage of PVST+?

A. PVST+ optimizes performance on the network through automatic selection of the root bridge.
B. PVST+ optimizes performance on the network through load sharing using multiple root bridges.
C. PVST+ reduces bandwidth consumption compared to traditional implementations of STP that use CST.
D. PVST+ requires fewer CPU cycles for all the switches in the network.

B. PVST+ optimizes performance on the network through load sharing using multiple root bridges.

In which two port states does a switch learn MAC addresses and process BPDUs in a PVST network? (Choose two.)

A. Blocking
B. Disabled
C. Forwarding
D. Learning
E. Listening

C. Forwarding
D. Learning

What two features does Spanning Tree Protocol (STP) provide to ensure proper network operations? (Choose two.)

A. Implementing VLANs to contain broadcasts
B. Link-state dynamic routing that provides redundant routes
C. Redundant links between Layer 2 switches
D. Removing single points of failure with multiple Layer 2 switches
E. Static default routes

C. Redundant links between Layer 2 switches
D. Removing single points of failure with multiple Layer 2 switches

Which PVST+ feature ensures that configured switch edge ports do not cause Layer 2 loops if a port is mistakenly connected to another switch?

A. BPDU guard
B. Extended system ID
C. PortFast
D. PVST+

A. BPDU guard

What is an advantage of using STP in a LAN?

A. It combines multiple switch trunk links into a logical port channel link to increase bandwidth.
B. It decreases the size of the failure domain.
C. It provides firewall services to protect the LAN.
D. It temporarily disables redundant paths to stop Layer 2 loops.

D. It temporarily disables redundant paths to stop Layer 2 loops.

Which two statements regarding a PortFast enabled switch port are true? (Choose two.)

A. The port immediately transitions from blocking to forwarding state.
B. The port immediately transitions from listening to forwarding state.
C. The port immediately processes any BPDUs before transitioning to the forwarding state.
D. The port sends DHCP requests before transitioning to the forwarding state.
E. The port should never receive BPDUs.

A. The port immediately transitions from blocking to forwarding state.
E. The port should never receive BPDUs.