ZyXEL Communications MWR222 - V1.0 Manual page 231

Table 80 Subnet Mask - Identifying Network Number
IP Address (Binary)
Subnet Mask (Binary)
Network Number
Host ID
By convention, subnet masks always consist of a continuous sequence of ones
beginning from the leftmost bit of the mask, followed by a continuous sequence
of zeros, for a total number of 32 bits.
Subnet masks can be referred to by the size of the network number part (the bits
with a "1" value). For example, an "8-bit mask" means that the first 8 bits of the
mask are ones and the remaining 24 bits are zeroes.
Subnet masks are expressed in dotted decimal notation just like IP addresses.
The following examples show the binary and decimal notation for 8-bit, 16-bit,
24-bit and 29-bit subnet masks
Table 81 Subnet Masks
BINARY
1ST
OCTET
8-bit mask 11111111
16-bit 11111111
mask
24-bit 11111111
MWR222 User's Guide
1ST 2ND
OCTET: OCTET:
(192) (168)
11000000 10101000
11111111 11111111 11111111 00000000
11000000 10101000 00000001
2ND 3RD
OCTET OCTET
00000000 00000000
11111111 00000000
11111111 11111111
231
3RD 4TH
OCTET: OCTET
(1) (2)
00000001 00000010
00000010
DECIMAL
4TH
OCTET
00000000 255.0.0.0
00000000 255.255.0.0
00000000 255.255.255.0