单选题 定义一个用于封禁ICMP协议而只允许转发166.129.130.0/24子网的ICMP数据包的访问控制列表，Cisco路由器的正确配置是______。
  • A.access-list 198 permit icmp 166.129.130.0 255.255.255.0 any access-list 198 deny icmp any any access-list 198 permit ip any any
  • B.access-1ist 198 permit icmp 166.129.130.0 0.0.0 255 any access-list 198 deny icmp any any access-list 198 permit ip any any
  • C.access-list 99 permit icmp 166.129.130.0 0.0.0 255 any access-list 99 deny icmp any any access-list 99 permit ip any any
  • D.access-list 100 permit icmp 166.129.130.0 0.0.0 255 any access-list 100 permit ip any any access-list 100 deny icmp any any
【正确答案】 B
【答案解析】[解析] 封禁ICMP协议属于配置扩展访问控制列表，所以表号范围为100～199或2000～2699，格式为：access-list access-list-number{permit|deny}protocol source wildcard-mask destination wildcard-mask[operator][operand]。因为wildcard-mask为子网掩码的反码，所以根据以上描述，本题选项B正确。