🚀 go-pugleaf

In article <CM5JM7.D19@cup.hp.com> of comp.sys.novell,
  mintz@cup.hp.com (Ken Mintz) writes:
> Mark Landin (landin@cherokee.nsuok.edu) wrote:
> > Can you subnet a Class C address, say by using a mask like 255.255.255.128?
> 
>   Not 128 specifically, but certainly other values, such as 192, 224 etc.
>   The problem with 128 per se is that that creates a one-bit subnet id.
>   Since all-zero and all-one values have special meaning, subnet id and host
>   id fields must comprise at least __two__ bits each.

Nope, sorry.  Not for a *network* number.  However, all 0 and all 1
for a *host* number are the clueless and the broadcast addresses,
respectively.

Hence, a one-bit subnet mask is perfectly valid, albeit a bit silly.

However, the subnet mask 255.255.255.254 would be invalid, since each
subnet would consist of only the clueless and the broadcast address.

> PS:  Some implementations do permit one-bit subnet ids, but this is non-
> conformant.

No, they are not.  Any application that does *not* permit a one-bit
subnet id is nonconformant.

	/hpa

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