On 27/02/11 06:46, Always Learning wrote: > Octets > > Thanks for pointing-out my misunderstanding. > > I'll remember 2 octets are really 2 characters (IBM's bytes) = 2 digits, > 4 octal numbers or 4 hexadecimal numbers. This is a confusing summary. 3 bits = 1 octal number (values 0-7) 4 bits = 1 nibble (values 0-15 or in hex 0x0-0xF) 8 bits = 2 nibbles = 1 byte or 1 octet (values 0-255 or in hex 0x00-0xFF) Don't mix in octal numbers, as that's a completely different numeric system which is very seldom used nowadays. Octal numbers are smaller than nibbles, which is usually the smallest unit referred to in today's computers. IPv4 uses 32 bits addresses, hence 4 bytes (4 bytes * 8 bits per byte = 32 bits). Organised into 4 "group", separated by dot. Each "group" contains 1 byte, where user interfaces uses decimal notation, with values from 0 to 255 IPv6 uses 128 bits addresses, hence 16 bytes (16 bytes * 8 bits per byte = 128 bits). Organised into 8 "groups" separated by colon. Each "group" contains of 2 bytes, where user interfaces uses hexadecimal notation, with values 0x0000 to 0xFFFF. That's basically it. kind regards, David Sommerseth