在一台Cisco路由器上，只允许IP地址为212.78.4.100/24的主机和202.34.76.64/26子网上的所有主机远程登录路由器，下列正确的access-list配置是（）
A．Router(config) # access-list 30 permit 202.34.76.64 0.0.0.63
Router(config) # access-list 30 permit 212.78.4.100
Router(config) # access-list 30 deny any
Router(config) # line vty 0 5
Router(config-line) # access-class 30 in
B．Router(config) # access-list 30 permit 202.34.76.64 0.0.0.192
Router(config) # access-list 30 permit 212.78.4.100
Router(config) # access-list 30 deny any
Router(config) # line vty 0 5
Router(config-line) # access-class 30 in
C．Router(config) # access-list 30 deny any
Router(config) # access-list 30 permit 202.34.76.64 0.0.0.63
Router(config) # access-list 30 permit 212.78.4.100
Router(config) # line vty 0 5
Router(config-line) # access-class 30 in
D．Router(config) # access-list 30 permit 202.34.76.64 255.255.255.192
Router(config) # access-list 30 permit 212.78.4.100
Router(config) # access-list 30 deny any
Router(config) # line vty 0 5
Router(config-line) # access-class 30 in
参考答案：A
解析：
由202.34.76.64/26的字网掩码255.255.255.192可以算出反码为0.0.0.63.再由定义格式可知A正确。