1. [单选题]How many usable IP addresses can you get from a conventional Class C address?
  A. 128 
  B. 192 
  C. 254 
  D. 256 
  E. 510 
 
2. [单选题]下列哪个network命令会告知此路由器开始使用IP地址为10.1.1.1、10.1.100.1和10.1.120.1的接口上的OSPF()
  A. network 10.0.0.0 255.0.0.0 area 0 
  B. network 10.0.0.0 0.255.255.255 area 0 
  C. network 10.0.0.1 0.0.0.255 area 0 
  D. network 10.0.0.1 0.0.255.255 area 0 
 
3. [单选题]默认情况下,RIP定期发送路由更新的时间是()
  A. 15S 
  B. 30S 
  C. 60S 
  D. 90S