Which two of these are characteristics of Metro Ethernet? （）

多项选择题Which two of these Metro Internet services map to E-LAN services that are defined by the MEF?（）

A. Ethernet Private Line
B. Ethernet Wire Service
C. Ethernet Relay Service
D. Ethernet Multipoint Service
E. Ethernet Relay Multipoint Service

多项选择题Which three of these Metro Ethernet services map to E-Line services that are defined by the MEF?（）

A. Ethernet Private Line
B. Ethernet Wire Service
C. Ethernet Relay Service
D. Ethernet Multipoint Service
E. Ethernet Relay Multipoint Service

单项选择题What is the recommended practice regarding UDLD when implementing it in all fiber-optic LAN ports?（）

A. Adjust the default hello timers to three seconds for aggressive mode.
B. Enable it in global mode and on every interface you need to support.
C. Enable it in global mode to support every individual fiber-optic interface.
D. Enable it to create channels containing up to eight parallel links between switches.
E. Enable it in global mode to support every individual fiber optic and Ethernet interface.

多项选择题Which two of these are recommended practices with trunks? （）

A. use ISL encapsulation
B. use 802.1q encapsulation
C. set ISL to desirable and auto with encapsulation negotiate to support ILS protocol negotiation
D. use VTP server mode to support dynamic propagation of VLAN information across the network
E. set DTP to desirable and desirable with encapsulation negotiate to support DTP protocol negotiation.

单项选择题Why is STP required when VLANs span access layer switches?（）

A. to ensure a loop-free topology
B. to protect against user-side loops
C. in order to support business applications
D. because of the risk of lost connectivity without STP
E. for the most deterministic and highly available network topology