单选题What is used as label in cell-based MPLS ？（）A VPIB VCIC VPI and VCID Specific 4 bytes labelE None of above

第1题：

What is the label for MPLS over ATM？（）

• A、VPI 16
• B、DLCI
• C、VPI and VCI
• D、circuit number
• E、PVC and SVC

第2题：

What are the four fields in an MPLS label？（）

• A、version
• B、experimental
• C、label
• D、protocol
• E、TTL
• F、bottom-of-stack indicato

第3题：

第4题：

Using more than one label on a single packet is required in what context？（）

• A、MPLS TE
• B、MPLS VPN
• C、When CEF switching and Label switching is done
• D、In all the above circumstances

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：

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7题：

What are the "bound IP addresses" used for in LDP？（）

• A、For each such address and mask /32, one label binding is created.
• B、As the TCP endpoint, IP addresses are used by the LDP session.
• C、These addresses are used to find the label binding to put in the LFIB, by looking up these IP addresses in the routing table.
• D、These addresses are used for penultimate hop popping (PHP) when forwarding packets to the next router directly. 

第8题：

There is MPLS VPN traffic traversing through a TE intermediate router. What is the MPLS packet labelstack sequence （from outer to inner） for the VPN traffic on this router？（）

• A、TE label， IGP label， VPN label
• B、IGP label， TE label， VPN label
• C、TE label， VPN label， IGP label
• D、VPN label， IGP label， TE label
• E、IGP label， VPN label， TE label

第9题：

As a network administrator, you are required to deploy MPLS technology. During the deployment, it is recommended to apply conditional label advertising. What is most probably the reason for that?（）

• A、to enable label switching on the frame mode interface
• B、to restrict MPLS availability to predefined time periods
• C、to restrict end users from seeing the routers in the MPLS network
• D、to restrict label switching to a limited number of networks

第10题：

What is the action of "pop" in the context of MPLS switching？（）

• A、It removes the top label in the MPLS label stack.
• B、It adds a top label in MPLS label stack.
• C、It replaces the top label in the MPLS label stack with another value.
• D、It replaces the top label in the MPLS label stack with a set of labels.
• E、None of above.