NETGEAR RT338 Reference Manual page 33

Table 1-2 lists the additional subnet mask bits in dotted-decimal notation. To use the table, write
down the original class netmask and replace the 0 value octets with the dotted-decimal value of the
additional subnet bits. For instance, to partition your Class C network 204.247.203.0 with subnet
mask 255.255.255.0 into 16 subnets (4 bits), the new subnet mask becomes 255.255.255.240.
Table 1-2. Netmask Notation Translation Table for One Octet
Number of Bits
1
2
3
4
5
6
7
8
Table 1-3 displays several common netmask values in both the dotted-decimal and the
masklength formats.
Table 1-3. Netmask Formats
Dotted-Decimal
255.0.0.0
255.255.0.0
255.255.255.0
255.255.255.128
255.255.255.192
255.255.255.224
255.255.255.240
255.255.255.248
255.255.255.252
255.255.255.254
255.255.255.255
Introduction
Dotted-Decimal Value
128
192
224
240
248
252
254
255
Masklength
/8
/16
/24
/25
/26
/27
/28
/29
/30
/31
/32
Reference Guide for the Model RT338 ISDN Router
1-11