1. [单选题]From where does a small network typically get its IP network addresses or IP block?
A. From the Internet Domain Name Registry (IDNR)
B. From the Internet Assigned Numbers Authority (IANA．
C. From the Internet Service Provider (ISP)
D. From the Internet Architecture Board (IAB．
E. None of the above
2. [单选题]扩展ACL和标准ACL的区别（）。
A. 标准的ACL在禁止和允许方面比扩展的ACL更高的精度
B. 扩展的ACL核查数据包的源地址(source address)和目标地址和端口号
C. 他们都可以查端口号
D. 他们都可以查特殊协议和其他参数
3. [单选题]Given that you have a class B IP address network range, which of the subnet masks below will allow for 100 subnets with 500 usable host addresses per subnet?
A. 255.255.0.0
B. 255.255.224.0
C. 255.255.254.0
D. 255.255.255.0
E. 255.255.255.224
4. [单选题]配置路由器特权用户“加密密码”的命令是：()
A. password
B. enable password
C. enable secret
D. passwd
5. [单选题]OSPF骨干区的区域编号为（）
A. 0.0.0.1
B. 255
C. 0.0.0.0
D. 255.255.255.255
