ZyXEL Communications ZyXEL Dimension ES-2108 - Manual (Page 265)

ES-2108 Series User’s Guide
Appendix B IP Addresses and Subnetting 265
Figure 118 Subnetting Example: Before Subnetting
You can “borrow” one of the host ID bits to divide the network 192.168.1.0 into two separate
sub-networks. The subnet mask is now 25 bits (255.255.255.128 or /25).
The “borrowed” host ID bit can have a value of either 0 or 1, allowing two subnets;
192.168.1.0 /25 and 192.168.1.128 /25.
The following figure shows the company network after subnetting. There are now two sub-
networks, A and B.