1. [单选题]After working on a router, some problems arise and you wish to view the commands that you recently entered. Which IOS command opens the history buffer and displays the most recently entered commands?
A. Show history
B. Show buffers
C. Show typed commands
D. Show terminal buffer
E. Show command
F. F. None of the above
2. [单选题]当配置一个CISCO的路由器时，缺省的DR和BDR优先级是（）。
B. 1
C. 16
D. 255
3. [单选题]下列哪一个通配符掩码与子网172.16.64.0/27的所有主机匹配（）。
A. 255.255.255.0
B. 255.255.224.0
C. 0.0.0.31
D. 0.0.31.255
