Changing the subnet to enable more PC connections

I think this is probably brutally simple to do since I can't find any
information on it but....

In my network we have an IP range of 192.168.100.x on a subnet of
255.255.255.0. and are about to exceed the available number of IP addreses.
I figure the simplest thing to do is just change the subnet to 255.255.0.0
and soldier on but am concerned with how this may affect the domain
controllers.... of which we have 4 Windows 2000 servers (SP4) including an
Exchange 2000 server. We also use ISA but it is only on a member server.

I found an MS site about changing the IP of a DC and it appeared to be
simply changing the IP in the usual fashion. If you can do that on a DC, I
would imagine changing the subnet would have no problems either but I need
to be sure.

I have one DC which does nothing but run as a DC, I have set up another
server with which to test DHCP. My plan is simply to change the subnet on
the DC, put the test DHCP server on the same subnet (255.255.0.0), disable
the current DHCP server and then test with a workstation by releasing and
renewing its IP address. This would be a consequence free way of trying it
out the basics I think, but I still need to know if there is anything else
to consider with respect replication between DC's... AD, DNS, FRS etc.

Any help would be appreciated.

Cheers,

Jeff

It shouldn't cause a problem. I would just add the new IP as a second IP
address to be safe.


"Jeff Brandon" <asfd> wrote in message
news:(E-Mail Removed)...
> I think this is probably brutally simple to do since I can't find any
> information on it but....
>
> In my network we have an IP range of 192.168.100.x on a subnet of
> 255.255.255.0. and are about to exceed the available number of IP
addreses.
> I figure the simplest thing to do is just change the subnet to 255.255.0.0
> and soldier on but am concerned with how this may affect the domain
> controllers.... of which we have 4 Windows 2000 servers (SP4) including an
> Exchange 2000 server. We also use ISA but it is only on a member server.
>
> I found an MS site about changing the IP of a DC and it appeared to be
> simply changing the IP in the usual fashion. If you can do that on a DC, I
> would imagine changing the subnet would have no problems either but I need
> to be sure.
>
> I have one DC which does nothing but run as a DC, I have set up another
> server with which to test DHCP. My plan is simply to change the subnet on
> the DC, put the test DHCP server on the same subnet (255.255.0.0), disable
> the current DHCP server and then test with a workstation by releasing and
> renewing its IP address. This would be a consequence free way of trying it
> out the basics I think, but I still need to know if there is anything else
> to consider with respect replication between DC's... AD, DNS, FRS etc.
>
> Any help would be appreciated.
>
> Cheers,
>
> Jeff
>
>

Rob,

Thanks for your response... Is this something you have ever tried or heard
of anyone else trying? My gut tells me it shouldn't be a problem but my head
(and experience) tells me that Windows can be a bit unpredictable sometimes.
Basically me real concern is the Exchange Server and to a lesser extent the
ISA server.

Cheers,

Jeff


"Rob Elder, MVP-Networking" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> It shouldn't cause a problem. I would just add the new IP as a second IP
> address to be safe.
>
>
> "Jeff Brandon" <asfd> wrote in message
> news:(E-Mail Removed)...
> > I think this is probably brutally simple to do since I can't find any
> > information on it but....
> >
> > In my network we have an IP range of 192.168.100.x on a subnet of
> > 255.255.255.0. and are about to exceed the available number of IP
> addreses.
> > I figure the simplest thing to do is just change the subnet to
255.255.0.0
> > and soldier on but am concerned with how this may affect the domain
> > controllers.... of which we have 4 Windows 2000 servers (SP4) including
an
> > Exchange 2000 server. We also use ISA but it is only on a member server.
> >
> > I found an MS site about changing the IP of a DC and it appeared to be
> > simply changing the IP in the usual fashion. If you can do that on a DC,
I
> > would imagine changing the subnet would have no problems either but I
need
> > to be sure.
> >
> > I have one DC which does nothing but run as a DC, I have set up another
> > server with which to test DHCP. My plan is simply to change the subnet
on
> > the DC, put the test DHCP server on the same subnet (255.255.0.0),
disable
> > the current DHCP server and then test with a workstation by releasing
and
> > renewing its IP address. This would be a consequence free way of trying
it
> > out the basics I think, but I still need to know if there is anything
else
> > to consider with respect replication between DC's... AD, DNS, FRS etc.
> >
> > Any help would be appreciated.
> >
> > Cheers,
> >
> > Jeff
> >
> >
>
>

I am not sure if windows cares about that but you can't
change Subnet mask of class C ip Address to class B ip
address, this is first.

Good practice is to use 10.x.x.x ip range which is class A
address and it can be subnetted as you wish, but it's
native Subnet mask is 255.0.0.0 so you can calculate how
many hosts you can have on the same network.

The rest I've never tried and I really don't know, sorry.

Alex.


>-----Original Message-----
>I think this is probably brutally simple to do since I
can't find any
>information on it but....
>
>In my network we have an IP range of 192.168.100.x on a
subnet of
>255.255.255.0. and are about to exceed the available
number of IP addreses.
>I figure the simplest thing to do is just change the
subnet to 255.255.0.0
>and soldier on but am concerned with how this may affect
the domain
>controllers.... of which we have 4 Windows 2000 servers
(SP4) including an
>Exchange 2000 server. We also use ISA but it is only on a
member server.
>
>I found an MS site about changing the IP of a DC and it
appeared to be
>simply changing the IP in the usual fashion. If you can
do that on a DC, I
>would imagine changing the subnet would have no problems
either but I need
>to be sure.
>
>I have one DC which does nothing but run as a DC, I have
set up another
>server with which to test DHCP. My plan is simply to
change the subnet on
>the DC, put the test DHCP server on the same subnet
(255.255.0.0), disable
>the current DHCP server and then test with a workstation
by releasing and
>renewing its IP address. This would be a consequence free
way of trying it
>out the basics I think, but I still need to know if there
is anything else
>to consider with respect replication between DC's... AD,
DNS, FRS etc.
>
>Any help would be appreciated.
>
>Cheers,
>
>Jeff
>

Hi Alex,

"Alex" <(E-Mail Removed)> wrote in message
>
> I am not sure if windows cares about that but you can't
> change Subnet mask of class C ip Address to class B ip
> address, this is first.

Huh? Can you elaborate?

>
> Good practice is to use 10.x.x.x ip range which is class A
> address and it can be subnetted as you wish, but it's
> native Subnet mask is 255.0.0.0 so you can calculate how
> many hosts you can have on the same network.

192.168..0.0 is also reserved for private use just like the
10.x.x.x ip range.

Yes this is the simplest thing to do. You won't have to change
the tcp/ip address of the existing machines just the subnet mask.

"Jeff Brandon" <asfd> wrote in message
news:(E-Mail Removed)...
> I think this is probably brutally simple to do since I can't find any
> information on it but....
>
> In my network we have an IP range of 192.168.100.x on a subnet of
> 255.255.255.0. and are about to exceed the available number of IP
addreses.
> I figure the simplest thing to do is just change the subnet to
255.255.0.0
> and soldier on but am concerned with how this may affect the domain
> controllers.... of which we have 4 Windows 2000 servers (SP4)
including an
> Exchange 2000 server. We also use ISA but it is only on a member
server.
>
> I found an MS site about changing the IP of a DC and it appeared to be
> simply changing the IP in the usual fashion. If you can do that on a
DC, I
> would imagine changing the subnet would have no problems either but I
need
> to be sure.
>
> I have one DC which does nothing but run as a DC, I have set up
another
> server with which to test DHCP. My plan is simply to change the subnet
on
> the DC, put the test DHCP server on the same subnet (255.255.0.0),
disable
> the current DHCP server and then test with a workstation by releasing
and
> renewing its IP address. This would be a consequence free way of
trying it
> out the basics I think, but I still need to know if there is anything
else
> to consider with respect replication between DC's... AD, DNS, FRS etc.
>
> Any help would be appreciated.
>
> Cheers,
>
> Jeff
>
>

On Fri, 5 Mar 2004 11:01:37 +1000, "Jeff Brandon" <asfd> wrote:

>I think this is probably brutally simple to do since I can't find any
>information on it but....
>
>In my network we have an IP range of 192.168.100.x on a subnet of
>255.255.255.0. and are about to exceed the available number of IP addreses.
>I figure the simplest thing to do is just change the subnet to 255.255.0.0
>and soldier on but am concerned with how this may affect the domain
>controllers.... of which we have 4 Windows 2000 servers (SP4) including an
>Exchange 2000 server. We also use ISA but it is only on a member server.

Domain controllers, or any system for that matter, doesn't care what
the subnet is. The subnet determins the logical network, and it's
used for network communications, that's all.

>I found an MS site about changing the IP of a DC and it appeared to be
>simply changing the IP in the usual fashion. If you can do that on a DC, I
>would imagine changing the subnet would have no problems either but I need
>to be sure.

Then now you're sure.

>I have one DC which does nothing but run as a DC, I have set up another
>server with which to test DHCP. My plan is simply to change the subnet on
>the DC, put the test DHCP server on the same subnet (255.255.0.0), disable
>the current DHCP server and then test with a workstation by releasing and
>renewing its IP address. This would be a consequence free way of trying it
>out the basics I think, but I still need to know if there is anything else
>to consider with respect replication between DC's... AD, DNS, FRS etc.

>Any help would be appreciated.

Change the subnet. No big deal.

Jeff

On Fri, 5 Mar 2004 11:47:45 +1000, "Jeff Brandon" <asfd> wrote:

>Thanks for your response... Is this something you have ever tried or heard
>of anyone else trying? My gut tells me it shouldn't be a problem but my head
>(and experience) tells me that Windows can be a bit unpredictable sometimes.
>Basically me real concern is the Exchange Server and to a lesser extent the
>ISA server.

I've done it. No issues. Changing the IP address to another logical
network will lose connectivity, but if you just change any of the
systems' netmasks now you'll never notice a difference. When you've
got them all changed, then you can add the new systems.

Jeff

>
>"Rob Elder, MVP-Networking" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed)...
>> It shouldn't cause a problem. I would just add the new IP as a second IP
>> address to be safe.
>>
>>
>> "Jeff Brandon" <asfd> wrote in message
>> news:(E-Mail Removed)...
>> > I think this is probably brutally simple to do since I can't find any
>> > information on it but....
>> >
>> > In my network we have an IP range of 192.168.100.x on a subnet of
>> > 255.255.255.0. and are about to exceed the available number of IP
>> addreses.
>> > I figure the simplest thing to do is just change the subnet to
>255.255.0.0
>> > and soldier on but am concerned with how this may affect the domain
>> > controllers.... of which we have 4 Windows 2000 servers (SP4) including
>an
>> > Exchange 2000 server. We also use ISA but it is only on a member server.
>> >
>> > I found an MS site about changing the IP of a DC and it appeared to be
>> > simply changing the IP in the usual fashion. If you can do that on a DC,
>I
>> > would imagine changing the subnet would have no problems either but I
>need
>> > to be sure.
>> >
>> > I have one DC which does nothing but run as a DC, I have set up another
>> > server with which to test DHCP. My plan is simply to change the subnet
>on
>> > the DC, put the test DHCP server on the same subnet (255.255.0.0),
>disable
>> > the current DHCP server and then test with a workstation by releasing
>and
>> > renewing its IP address. This would be a consequence free way of trying
>it
>> > out the basics I think, but I still need to know if there is anything
>else
>> > to consider with respect replication between DC's... AD, DNS, FRS etc.
>> >
>> > Any help would be appreciated.
>> >
>> > Cheers,
>> >
>> > Jeff
>> >
>> >
>>
>>
>