Re: all zeroes/all ones used in host IP's...

From: H. Peter Anvin (hpa@transmeta.com)
Date: Fri Jan 28 2000 - 19:09:48 EST


Followup to: <Pine.LNX.4.10.10001282146090.25919-100000@ps.cus.umist.ac.uk>
By author: Riley Williams <rhw@MemAlpha.CX>
In newsgroup: linux.dev.kernel
>
> 1. The relevant standard states that all IP addresses are
> classified as one of classes A, B, C or D depending only
> on the FIRST octet/byte thereof, as follows:
>
> 0 Reserved
> 1-127 Class A 8 bit
> 128-191 Class B 16 bit
> 192-223 Class C 24 bit
> 224-254 Class D
> 255 Reserved
>
> Class D appears to have some strange rules associated with it,
> and I can't claim to fully understand them, so I will not
> analyse it further.
>

Actually, that is...

        224-239 Class D Multicasting
        240-255 Class E Experimental (reserved)

Also, network 127 is reserved for host-local addressing.

These days, the class A/B/C distinction is academic, although the
numbering authorities still assign blocks out of the A, B or C ranges
roughly depending on block size. The cutoffs seem to be somewhere
around /10 or /11 and /16.

        -hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."

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