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有时会看到一些有关 ip 段的写法是这样的:“192.168.1.1/24”,这种写法叫 CIDR 无类域间路由。“/” 后面的数字控制前面 ip
地址的掩码,以表示后面有几位可以变。
具体解析如下:
网段区间 192.168.1.1/24
IP 地址 192.168.1.1,由 4 段 32 bit 组成,即
11000000 10101000 00000001 00000001
/24 表示子网掩码前 24 位为 1,后面为 0,子网掩码和 IP 地址按位与运算
11111111 11111111 11111111 00000000 11000000 10101000 00000001 00000001 &
---------------------------------------- 11000000 10101000 00000001 00000000
十进制为 192.168.1.0,得到网络地址
子网掩码中等于 0 的部分是后面 8 位,将网络地址的后 8 位设置为 1,即
11000000 10101000 00000001 11111111
十进制为 192.168.1.255,得到广播地址
总结
IP 段 192.168.1.0/24
IP 段 192.168.1.0 - 192.168.1.255
起始 IP 192.168.1.1 - 192.168.1.254
网络 192.168.1.0
掩码 255.255.255.0
广播 192.168.1.255
可用数 254