Archived from groups: microsoft.public.win2000.dns (
More info?)
In news:%23pwRmxWVEHA.2988@TK2MSFTNGP10.phx.gbl,
I.is.Who.I.am <iiswhoiam@mymailbox.org> posted their thoughts, then I
offered mine
> > As for the
> > IP of the DHCP server, I would set it to an IP on the respective
"subnet"
> > (loosely put) and set the mask to encompass both "subnets" so they
"appear"
> > to be one.
> Forgive my ignorance but I do not understand the last sentence fully,
> so let me
> try this example and see if I have it right.
> With a subnet mask of 255.255.255.0
> 1.a.local - DHCP/DNS/WINS/AD - IP of 192.168.3.5 and 192.168.2.2
> 1.b.local - DHCP/DNS/WINS/AD - IP of 192.168.2.5 and 192.168.3.2
> 3.a.local - Stand Alone w/ICS - IP of 192.168.3.1 and 192.168.2.1
> internal (one IP for each subnet which is the gateway for each subnet
> on the client machines)
> and 192.168.1.1 external understanding your recommendation against
> ICS, this is
> just for quick config until ICS is disabled. Realize I changed the
> IPs for a.local from 0.xxx to 2.xxx to avoid conflict with ICS.
>
> If I used each DHCP server as a backup to the other (80/20 rule) and
> used superscopes
> for this purpose, does each server require one or two IPs?
No problem, but maybe I should explain the masks a bit more. Are you
familiar with subnetting? IF not, let's break it down...
If I have an IP on one machine with:
192.168.3.5
and an IP on another machine with:
192.168.2.5
and both machines I will use this mask:
255.255.252.0
Both machines will now be able to communicate with each other without a
router. The mask is telling the machine that both of those IP address are on
the same network.
If you follow what I'm suggesting about the mask, you will not need two NICs
or two IP addresses (which will cause more confusion on setting up a machine
and issues with DNS and AD anyway).
To further explain:
The mask 255.255.252.0 is broken down into its binary bits:
11111111.11111111.11111100.00000000
Then we break down 192.168.3.5 into binary:
11000000.10101000.0000011.00000101
Then we break down 192.168.2.5
11000000.10101000.00000001.00000101
Now let's say 192.168.2.5 is trying to communicate with 192.168.3.5. The
machine with 192.168.2.5 is the "sending host". The sending host will then
takes it's own IP address and "ANDS" it to it's mask. (keep in mind it does
not know the mask of the destination host, it;'s just doing this to
determine whether its on the same network or not. If it is not on the same
network, the sending host will not just dump the packet on the wire to the
destination host, but rather send it to the router. What you're trying to do
is make both IP subnet ranges appear to all the machines that they are on
the same wire or subnet. Make sense?
The sending host will AND its own IP to the mask, and it will then AND the
destination IP to its own mask, then compares them. If the result is the
same, then it will send the packet directly on the wire. If the result is
different, then it means that the destination host is not on this network,
so therefore it sends it to the router to let the router handle it, since
its obviously somewhere else.
So anyway, "Anding is a process where we add up the bits. If there is a 1
and a 1 in the same column, the result is a 1. Any other combination is a 0.
11000000.10101000.00000001.00000101
11111111.11111111.11111100.00000000
__________________________________
11000000.10101000.00000000.00000000
Ok, now that same machine, 192.168.2.5 will take the destination IP address
and AND that to its own mask:
11000000.10101000.0000011.00000101
11111111.11111111.11111100.00000000
__________________________________
11000000.00000000.00000010.00000000
Then the sending host compares the results. The results above are exactly
the same. So therefore the sending hosts knows that the destingation host is
on the same subnet and will dump the packet directly on the wire. If the
results were different, it would have sent it to the router, but in this
case, which mirrors what your ip scheme is, they are the same using the
255.255.252.0 subnet.
Hence, what I;ve been trying to say. All you need is one NIC with one IP and
use 255.255.252.0 as the mask on both of your offices since you do not havce
a router and they are 'hubbed' together.
To further explain, a subnet of 255.255.252.0 will be able to handle 1024
hosts. It will encompass the whole 192.168.2.0, 3.0,
This will be plenty for your scenario.
All you need to do is create one DHCP scope for:
192.168.3.0 to 192.168.5.0 or whatever you want in between or more, since it
will handle the whole range or more.
You can split this between the two if you like with an 80/20 split for
backup.
Hope that explains it? Post back if not .....
--
Regards,
Ace
Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS-IS" with no warranties and confers no
rights.
Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory
HAM AND EGGS: A day's work for a chicken; A lifetime commitment for a
pig. --
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