Table B-1. Netmask Notation Translation Table For One Octet; Table B-2. Netmask Formats - NETGEAR PS104 Installation And Reference Manual

Although the preceding example uses the entire third octet for a subnet address, note that you are
not restricted to octet boundaries in subnetting. To create more network numbers, you need only
shift some bits from the host address to the network address. For instance, to partition a Class C
network number (192.68.135.0) into two, you shift 1 bit from the host address to the network
address. The new netmask (or subnet mask) is 255.255.255.128. The first subnet has network
number 192.68.135.0 with hosts 192.68.135.1 to 129.68.135.126, and the second subnet has
network number 192.68.135.128 with hosts 192.68.135.129 to 192.68.135.254.
Note: The number 192.68.135.127 is not assigned because it is the broadcast address
of the first subnet. And 192.68.135.128 is not assigned because it is the network address
of the second subnet.
Table B-1 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 B-1. Netmask Notation Translation Table for One Octet
Number of Bits
1
2
3
4
5
6
7
8
Table B-2 displays several common netmask values in both the dotted-decimal and the
masklength formats.
Table B-2. Netmask Formats
Dotted-Decimal
255.0.0.0
255.255.0.0
255.255.255.0
Understanding IP Addresses
Installation and Reference for the Model PS104/PS105/PS110 Print Server
Dotted-Decimal Value
128
192
224
240
248
252
254
255
Masklength
/8
/16
/24
B-5