A management domain typically contains a large amount of management information. Each individual item of（）information is an instance of a managed object type. The definition of a related set of managed（）types is contained in a Management Information Base (MIB) module. Many such MIB modules are defineD. For each managed object type it describes, a MIB（）defines not only the semantics and syntax of that managed object type, but also the method of identifying an individual instance so that multiple（）of the same managed object type can be distinguisheD. Typically, there are many instances of each managed object（）within a management domain.

Typically, there are many instances of each managed object（）within a management domain.

A．device

B．state

C．type

D．packet

以下网络中，属于广域网的有哪些

Ⅰ．以太总线网(Ethernet) Ⅱ．光纤分布式数字接口FDDI

Ⅲ．令牌环网(Token Ring) Ⅳ．异步传输模式ATM

Ⅴ．B-ISDN Ⅵ．公用分组交换网(X.25)

A．Ⅰ、Ⅱ和Ⅲ

B．Ⅱ、Ⅳ和Ⅴ

C．Ⅱ、Ⅴ和Ⅵ

D．Ⅳ、Ⅴ和Ⅵ