What is periodically multicasted （every 10 seconds） by the DIS on a LAN to ensure IS-IS Link StateDatabase accuracy？（） ["PSNP","CSNP","LSP","IIH","ISH"]
OLT通过（）获取ONU的往返延迟RTD（Round Trip Delay），从而指定 合适的均衡延时参数EqD（Equalization Delay），保证每个ONU发送数据时不会在分光器上产生冲突。 ["测距技术B、光模块突发控制","AES加密D、动态带宽分配"]
What SNMP message alerts the manager to a condition on the network?（） ["response","trap","cet","capture"]
Why do large OSPF networks use a hierarchical design?（） [" to confine network instability to single areas of the network."," to reduce the complexity of router configuration"," to speed up convergence"," to lower costs by replacing routers with distribution layer switches"," to decrease latency by increasing bandwidth"," to reduce routing overhead"]
生化药物的主要资源有（）、（）、（）、（）、微生物、（）。
地方分权型的课程管理模式
