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Subjectall zeroes/all ones used in host IP's...
On another mailing list I'm on there is a small discussion about
using "0's" in IP addresses. Nobody could categorically say
wether or not they are allowed or not including myself, so I
hunted down RFC 1123, and found the relevant section.

Here it is:

IP addresses are not permitted to have the value 0 or -1 for
any of the <Host-number>, <Network-number>, or <Subnet-
number> fields (except in the special cases listed above).
This implies that each of these fields will be at least two
bits long.

Now I interpreted that as meaning that none of the octets in an
IP address could be 0 or "-1" in either the network/subnet or
host portions of a valid host IP. The definition of "-1" is "all
ones" in the host or network/subnet portion.

I interpret the above as meaning that it is not legal to have a
network like this: or

with hosts through or with hosts through

The first zero makes it illegal no? Could someone in the know
please clarify this as it has been bugging me for some time and
nobody else seems to be able to say with 100% certainty what the
proper rule is. Also, would a network like: be illegal?

Someone has suggested that my interpretation is wrong, and if
that is indeed so, I'd like to know the proper interpretation and
share it with everyone.

I looked through some of the kernel source and couldn't find any
special handling of such addresses.

Thanks very much in advance.
Take care!

Mike A. Harris Linux advocate
Computer Consultant GNU advocate
Capslock Consulting Open Source advocate

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