把1721617818划分成16个子网并列出划分明细和掩码

首先，将172.16.178/18转换为二进制： 10101100.00010000.1011 0010.00000000

由于需要划分成16个子网，需要将原有的网络位中的某些位划分为子网位。将16写成二进制是0001 0000，需要借用4位二进制位作为子网位。

划分明细如下：

| 子网号 | 网络地址 | 第一个可用地址 | 最后一个可用地址 | 广播地址 | 子网掩码 | |--------|---------------------|---------------------|---------------------|-------------------|---------------------| | 1 | 172.16.160.0/22 | 172.16.160.1 | 172.16.163.254 | 172.16.163.255 | 255.255.252.0 (22位) | | 2 | 172.16.164.0/22 | 172.16.164.1 | 172.16.167.254 | 172.16.167.255 | 255.255.252.0 (22位) | | 3 | 172.16.168.0/22 | 172.16.168.1 | 172.16.171.254 | 172.16.171.255 | 255.255.252.0 (22位) | | 4 | 172.16.172.0/22 | 172.16.172.1 | 172.16.175.254 | 172.16.175.255 | 255.255.252.0 (22位) | | 5 | 172.16.176.0/22 | 172.16.176.1 | 172.16.179.254 | 172.16.179.255 | 255.255.252.0 (22位) | | 6 | 172.16.180.0/22 | 172.16.180.1 | 172.16.183.254 | 172.16.183.255 | 255.255.252.0 (22位) | | 7 | 172.16.184.0/22 | 172.16.184.1 | 172.16.187.254 | 172.16.187.255 | 255.255.252.0 (22位) | | 8 | 172.16.188.0/22 | 172.16.188.1 | 172.16.191.254 | 172.16.191.255 | 255.255.252.0 (22位) | | 9 | 172.16.192.0/22 | 172.16.192.1 | 172.16.195.254 | 172.16.195.255 | 255.255.252.0 (22位) | | 10 | 172.16.196.0/22 | 172.16.196.1 | 172.16.199.254 | 172.16.199.255 | 255.255.252.0 (22位) | | 11 | 172.16.200.0/22 | 172.16.200.1 | 172.16.203.254 | 172.16.203.255 | 255.255.252.0 (22位) | | 12 | 172.16.204.0/22 | 172.16.204.1 | 172.16.207.254 | 172.16.207.255 | 255.255.252.0 (22位) | | 13 | 172.16.208.0/22 | 172.16.208.1 | 172.16.211.254 | 172.16.211.255 | 255.255.252.0 (22位) | | 14 | 172.16.212.0/22 | 172.16.212.1 | 172.16.215.254 | 172.16.215.255 | 255.255.252.0 (22位) | | 15 | 172.16.216.0/22 | 172.16.216.1 | 172.16.219.254 | 172.16.219.255 | 255.255.252.0 (22位) | | 16 | 172.16.220.0/22 | 172.16.220.1 | 172.16.223.254 | 172.16.223.255 | 255.255.252.0 (22位) |

子网掩码的计算方法为：先将原有的网络掩码转换为二进制，再将要作为子网位的二进制位变为0，其余位变为1，最后转换回十进制即为子网掩码