[名词解释] PSC协议

锐捷路由器默认的同步口的封装方式是？（） ["A、frame-relay","B、X.25","C、Ppp","D、hdlc"] 下列各项中属于大气常定成分的是（）。 ["A、水汽（H₂O）","B、氧气（O₂）","C、氯氟烃（CFCs）","D、臭氧（O₃）"] 不属于开发管理信息系统的方法的流程是（）。 ["系统分析","系统设计","系统实施","系统反馈"] PS协议 当学生A用两台Star—R2624路由器在做路由器广域网口连通实验时误将本端口路由器V.35线缆的插头插倒了。结果发现PING直连的路由器不通，请问此时需要查看路由器的状态应该是（） ["A、Serial 0 is up，line protocol is down","B、Serial 0 is down，line protocol is down","C、Serial 0 is down，line protocol is up","D、Serial 0 is administratively down，line protocol is"] PSC协议