D-Link DI-206 - Manual (Page 173)

DI-206 ISDN Remote Router
Appendix B - IP Concepts 161
IP Class Subnet Mask
Class A 255.0.0.0
Class B 255.255.0.0
Class C 255.255.255.0
Subnet mask settings other than those listed above add significance to the interpretation of
bits in the IP address. The bits of the subnet mask correspond directly to the bits of the IP
address. Any bit an a subnet mask that is to correspond to a net ID bit in the IP address must
be set to 1.