What does UDLD stand for？（）A、UniDirectional Loop DetectionB、Unspecified Distribution Label DetectionC、Unified Distribution Label DirectionD、UniDirectional Link Detection

第1题：

第2题：

Which option describes the incorrect usage of the Label Distribution method？（）

• A、LDP is primarily used in internal networks of MPLS-VPN providers.
• B、MP-BGP is used for label distribution for VPN customer routes.
• C、Directed LDP is used for label distribution in L2-VPN Attachement Circuits.
• D、MP-BGP is used for label distribution in MPLS Traffic Engineered networks.

第3题：

第4题：

On switch R1 you issue the "udld enable" global command.  What does this command accomplish？ （）

• A、 Enables all fiber-optic LAN ports for Unidirectional LINK Detection （UDLD）
• B、 Enables all copper media LAN ports Unidirectional Link Detection （UDLD）
• C、 Overrides the default UDLS setting for all ports
• D、 Globally enables all ports on the device for Unidirectional Link Detection （UDLS）
• E、 None of the other alternatives apply

第5题：

In the context of MPLS，what is the correct action to be performed when an aggregate label is received ？（）

• A、It adds the VPN label into the top label in the MPLS label stack
• B、It replaces the top label in the MPLS label stack with a VPN label and propagates
• C、It replaces the bottom label in the MPLS label stack with a VPN label and propagates
• D、It removes the top label in the MPLS label stack and does a Layer 3 lookup on underlying IP packets
• E、None of above

第6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7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8题：

第9题：

Which of the following is true regarding Label Distribution Protocol （LDP）？（）

• A、It is a label distribution protocol for MPLS
• B、It is a set of procedures and messages by which LSRs establish Label Switch Paths （LSPs） through a network
• C、Tag distribution Protocol （TDP） was the basis for LDP
• D、All of the above are true

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.