Subnet Mask - D-Link DSL-300T User Manual

Subnet Mask

In the absence of subnetworks, standard TCP/IP addressing may be used by specifying subnet masks as shown
below.
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.
DSL-300T ADSL Modem User's Guide
IP Class
Class A
Class B
Class C
49
Subnet Mask
255.0.0.0
255.255.0.0
255.255.255.0