Re: Losing Static IP Address / Changing to Automatic (expects DHCP)

From: Fred Marshall (fmarshallx_at_remove_the_x.acm.org)
Date: 06/17/04 

Date: Thu, 17 Jun 2004 07:19:33 -0700

"Chuck" <none@example.net> wrote in message
news:qhi1d0diqv310a04bkd3r6rcu27b0uimkf@4ax.com...
> On Wed, 16 Jun 2004 15:17:11 -0700, "Fred Marshall"
> <fmarshallx@remove_the_x.acm.org> wrote:
>
> >Thanks for the reply.
> >
> >Well, what if the static IP address *were* already assigned? I
understand
> >that would create a conflict. However, what does that have to do with
the
> >client setup changing all by itself without intervention? There is no
DHCP
> >service running anywhere.
> >
> >Fred
>
> Fred / Albatross,
>
> In Windows XP, you have the ability to have a General and an Alternate
> Configuration. Generally, it is used with DHCP set for General (so any
DHCP
> server can assign an ip address and everything else), and APIPA (automatic
self
> assignment) set for Alternate (so if no DHCP server is available, the
system
> issues an APIPA address, which is chosen to not equal one already in use
on the
> network).
>
> In your case, you assigned a fixed address for General. If that address
is in
> use, it then self assigns an APIPA address.
>
> You have the option to assign an Alternate Configuration using a second
fixed
> address of your choice, rather than allow APIPA.
>
> Look at Example 2 in the document for an alternate scenario which may
apply in
> your case.
>
> <http://support.microsoft.com/default.aspx?scid=kb;en-us;220874>
>
> Cheers,
> Chuck
> Paranoia comes from experience - and is not necessarily a bad thing.

Chuck,

I read the article and I looked at an XP Home system. I didn't find an
Alternate entry or section although I did find a way to add an IP address
using Advanced. It's not clear at all what using that latter approach will
do.

So, I'm curious about the Alternate that you mentioned.

I also read 308007 and it appears that the configuration I'm working with is
unconventional:

Peer to peer network with no router or ICS-configured computer or other DHCP
server.
IP addresses are static in 192.168.1.x range with 255.255.255.0 subnet mask.
There is no gateway entered in any of the computers.

Two of the XP systems have switched from static IP addressing to APIPA and
this is accompanied by the setting "Use the following IP address:" being
changed to "Obtain an IP address automatically".

Of course, the APIPA addresses are incompatible with the static addresses
that are set up in the other machines on the network - so connectivity is
lost when this happens.

I have a notion, perhaps one that is unjustified, that using static IP
addresses is better - particularly when setting up a network and assuring
that things are working. It avoids the time it takes for a network to
figure out who is who as would be the case with DHCP or APIPA. Now, I must
admit that I almost never work on peer-to-peer networks such as this one.
However, the occurrence concerns me because:

For internal security, one might turn off DHCP on a router and use static
addresses.
So, what happens with XP clients if:
Somebody comes in with a laptop that has the same IP address set up as is on
one of the other computers (call it #2).
#2 is shut off when the laptop is connected.
Then, #2 is subsequently turned on.
There is, as above, No DHCP.
There is an IP address conflict.

Does #2 lose the setting "Use the following IP address" and automatically
switch to "Obtain an IP address automatically" and, therefore, get an APIPA
address - never to return without human intervention?

Thanks,

Fred
Does the

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