单选题If a port configured with STP loop guard stops receiving BPDUs，the port will be put into which state？（）A learning stateB listening stateC forwarding stateD root-inconsistent state

第1题：

Switch R1 has been configured with the root guard feature.  What statement is true if the spanning  tree enhancement Root Guard is enabled？ （）

• A、 If BPDUs are not received on a non-designated port， the port is moved into the STP loop- inconsistent blocked state
• B、 IF BPDUs are received on a PortFast enabled port， the port is disabled.
• C、 If superior BPDUs are received on a designated port， the interface is placed into the root- inconsistent blocked state.
• D、 If inferior BPDUs are received on a root port， all blocked ports become alternate paths to the  root bride.

第2题：

Loop guard and UniDirectional Link Detection both protect against Layer 2 STP loops. In which two ways does loop guard differ from UDLD in loop detection and prevention？（）

• A、Loop guard can be used with root guard simultaneously on the same port on the same VLAN while UDLD cannot.
• B、UDLD protects against STP failures caused by cabling problems that create one-way links.
• C、Loop guard detects and protects against duplicate packets being received and transmitted on different ports.
• D、UDLD protects against unidirectional cabling problems on copper and fiber media.
• E、Loop guard protects against STP failures caused by problems that result in the loss of BPDUs from a designated switch port.

第3题：

Which of the following characteristics describe the BPDU Guard feature（）

• A、ABPDU Guard port should only be configured on ports with PortFast enabled.
• B、BPDU Guard and PortFast should not be enabled on the same port.
• C、BPDU Guard is used to ensure that superior BPDUs are not received on a switch port.
• D、ABPDU Guard port receiving a BPDU will go into err-disablestate.
• E、ABPDU Guard port receiving a BPDU will be disabled.
• F、BPDU Guard can be enabled on any switch port.

第4题：

Which two statements correctly describe characteristics of the PortFast feature？ （）

• A、STP will be disabled on the port.
• B、PortFast can also be configured on trunk ports.
• C、PortFast is required to enable port-based BPDU guard.
• D、PortFast is used for both STP and RSTP host ports.
• E、PortFast is used for STP-only host ports.

第5题：

Examine the following options，which Spanning Tree Protocol （STP） protection mechanism disables aswitch port if the port receives a Bridge Protocol Data Unit （BPDU）？（）

• A、Uplink Fast
• B、Port Fast
• C、BPDU Guard
• D、Root Guard

第6题：

What is the STP root guard feature designed to prevent？（）

• A、a root port being transitioned to the blocking state
• B、a port being assigned as a root port
• C、a port being assigned as an alternate port
• D、a root port being transitioned to the forwarding state

第7题：

After configuring FabricPath， the following appears in the syslog：  %STP-2-L2GW_BACKBONE_BLOCK： L2 Gateway Backbone port inconsistency blocking port port-channel100 on VLAN0010.  What is the cause of this message？ （）      

• A、 STP must be disabled； message indicates that STP is enabled.
• B、 STP is misconfigured； root guard must be disabled.
• C、 An inferior BPDU is received on a Cisco FabricPath edge port.
• D、 A superior BPDU is received on a Cisco FabricPath edge port.

第8题：

Loop guard and UniDirectional Link Detection both protect against Layer 2 STP loops. In which two ways does loop guard differ from UDLD in loop detection and prevention？ （）

• A、 Loop guard can be used with root guard simultaneously on the same port on the same VLAN while UDLD cannot
• B、 UDLD protects against STP failures caused by cabling problems that create one-way links.
• C、 Loop guard detects and protects against duplicate packets being received and transmitted on different ports
• D、 UDLD protects against unidirectional cabling problems on copper and fiber media.
• E、 Loop guard protects against STP failures caused by problems that result in the loss of BPDUs from a designated switch port.

第9题：

Which statement is true about loop guard？（）

• A、Loop guard only operates on interfaces that are considered point-to-point by the spanning tree.
• B、Loop guard only operates on root ports.
• C、Loop guard only operates on designated ports.
• D、Loop guard only operates on edge ports.

第10题：

Which two statements correctly describe UDLD？ （）

• A、Unidirectional link detection is achieved through monitoring STP BPDUs.
• B、It is recommended that it be enabled globally rather than on an individual port.
• C、When an error is detected， normal mode will disable a port.
• D、It is recommended that it be enabled in normal mode.
• E、It is recommended that it be used with the loop guard feature.