How many bits does EXP occupy in the MPLS label header？（）A、8B、4C、3D、1E、2

第1题：

How many bits represented in DSCP？

第2题：

Which two QoS classification and marking statements are true？（）

• A、 In a Frame Relay network， delay sensitive traffic is tagged with the discard eligible （DE） bit.
• B、 In an MPLS network， the three most significant bits of the DSCP or the IP precedence of the IP packet are copied into the MPLS EXP field
• C、 In an MPLS network， the MPLS EXP bits are used to identify up to 16 CoS values.
• D、 The differentiated services code point （DSCP） field consists of the first three bits of the IP precedence field in the header of an IP packet.
• E、 The 802.10 standard uses a three bitfield referred to as the user priority bits （PRI） to mark packets as belonging to a specific CoS.

第3题：

第4题：

Which statement correctly describes the disabling of IP TTL propagation in an MPLS network？（）

• A、The TTL field from the IP packet is copied into the TTL field of the MPLS label header at the ingress edge LSR
• B、TTL propagation cannot be disabled in an MPLS domain
• C、TTL propagation is only disabled on the ingress edge LSR
• D、The TTL field of the MPLS label header is set to 255
• E、The TTL field of the IP packet is set to 0

第5题：

In a frame ，the MPLS label is imposed（）.

• A、After the Layer3 header and before Layer2 header
• B、After the Layer2 header and before Layer3 header
• C、Within the Layer 3 header
• D、Before the layer 2 header

第6题：

Which two QoS classification and marking statements are true？ （）

• A、 In a Frame Relay network， delay sensitive traffic is tagged with the discard eligible （DE） bit.
• B、 In an MPLS network， the three most significant bits of the DSCP or the IP precedence of the IP packet are copied into the MPLS EXP field.
• C、 In an MPLS network， the MPLS EXP bits are used to identify up to 16 CoS values.
• D、 The differentiated services code point （DSCP） field consists of the first three bits of the IP precedence field in the header of an IP packet.
• E、 The 802.1Q standard uses a three bit field referred to as the user priority bits （PRI） to mark packets as belonging to a specific CoS.

第7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8题：

Which four of these are MPLS label header fields？ （）

• A、Label
• B、VPI VCI
• C、EXP
• D、TTL
• E、FCS
• F、S flag

第9题：

A router receives a packet from a neighbor with an MPLS shim header value of 0.What does the router do with this packet?（）

• A、It performs a label pop operation and an IP lookup.
• B、It performs a label swap operation and an IP lookup.
• C、It sends an error message toward the egress router.
• D、It sends an error message toward the ingress router.

第10题：

How many simultaneous Telnet sessions does a Cisco router support by default?（）

• A、1
• B、2
• C、3
• D、4
• E、5
• F、6