ZyXEL VFG6005 User Guide - Page 107

(192) (168) (1) (2) IP Address (Binary) Subnet Mask (Binary) Network Number Host ID 11000000 10101000 00000001 00000010 11111111 11111111 11111111 00000000 11000000 10101000 00000001 00000010 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 Subnet Masks BINARY 1ST OCTET 2ND OCTET 3RD OCTET 4TH OCTET DECIMAL 8-bit mask 11111111 00000000 00000000 00000000 255.0.0.0 16-bit mask 11111111 11111111 00000000 00000000 255.255.0.0 24-bit mask 11111111 11111111 11111111 00000000 255.255.255.0 98