The Simple Network Management Protocol(SNMP)is an(66)protocol that facilitates the exchange of management information between(67). It is part of the Transmission Control Protocol/Internet Protocol(TCP/IP)protocol suite. SNMP enables network(68)to manage network performance, find and sole network problems, and plan for(69)An SNMP -managed network consists of three key components: managed devices ,(70),and network -management systems .

A．Physical
B.Link
C.Network
D.Transport