classless IP Subnetting

Question

我想用给定的ip地址进行子网划分，如下所示
192.168.10.0/25
我的要求是我想每个子网30个地址。
子网0的nw地址是什么？
是192.168.10.0/27还是192.168.10.128/27？

Answer 1

的ipcalc工具可以回答这个问题为您：

Address: 192.168.10.0   11000000.10101000.00001010.0 0000000 
Netmask: 255.255.255.128 = 25 11111111.11111111.11111111.1 0000000 
Wildcard: 0.0.0.127    00000000.00000000.00000000.0 1111111 
=> 
Network: 192.168.10.0/25  11000000.10101000.00001010.0 0000000 (Class C) 
Broadcast: 192.168.10.127  11000000.10101000.00001010.0 1111111 
HostMin: 192.168.10.1   11000000.10101000.00001010.0 0000001 
HostMax: 192.168.10.126  11000000.10101000.00001010.0 1111110 
Hosts/Net: 126     (Private Internet) 


Subnets 

Netmask: 255.255.255.224 = 27 11111111.11111111.11111111.111 00000 
Wildcard: 0.0.0.31    00000000.00000000.00000000.000 11111 

Network: 192.168.10.0/27  11000000.10101000.00001010.000 00000 (Class C) 
Broadcast: 192.168.10.31   11000000.10101000.00001010.000 11111 
HostMin: 192.168.10.1   11000000.10101000.00001010.000 00001 
HostMax: 192.168.10.30   11000000.10101000.00001010.000 11110 
Hosts/Net: 30     (Private Internet) 


Network: 192.168.10.32/27  11000000.10101000.00001010.001 00000 (Class C) 
Broadcast: 192.168.10.63   11000000.10101000.00001010.001 11111 
HostMin: 192.168.10.33   11000000.10101000.00001010.001 00001 
HostMax: 192.168.10.62   11000000.10101000.00001010.001 11110 
Hosts/Net: 30     (Private Internet) 


Network: 192.168.10.64/27  11000000.10101000.00001010.010 00000 (Class C) 
Broadcast: 192.168.10.95   11000000.10101000.00001010.010 11111 
HostMin: 192.168.10.65   11000000.10101000.00001010.010 00001 
HostMax: 192.168.10.94   11000000.10101000.00001010.010 11110 
Hosts/Net: 30     (Private Internet) 


Network: 192.168.10.96/27  11000000.10101000.00001010.011 00000 (Class C) 
Broadcast: 192.168.10.127  11000000.10101000.00001010.011 11111 
HostMin: 192.168.10.97   11000000.10101000.00001010.011 00001 
HostMax: 192.168.10.126  11000000.10101000.00001010.011 11110 
Hosts/Net: 30     (Private Internet) 



Subnets: 4 
Hosts:  120 

而且，地址192.168.10.128已超出原/25的范围！