Is this actually going to work?

[William Buchanan]

Hi folks

I have 2 AD DC's (Win2k SP4). They both have 2 NIC's. 1 of the NIC's on both
servers share the IP address of 10.0.0.1 - the reason for this is so that in
the event of a failure of the main server, I take the network cable out of
the main server and plug it into the other so that the clients can continue
working (this is kit that we take out on the road so the other server is
only there for redundancy). So, only 1 of the 10.0.0.1 NIC's is plugged into
the network at any time.

However........ both servers keep on registering themselves in DNS with the
10.0.0.1 IP address. This is a problem as they need to reference each other
through the other NIC on their unique 192.168.0.* IP (this is for SQL server
replication). What happens is they suddenly decide that the other server's
IP address is 10.0.0.1 and go to use that IP - however, it being their own
IP as well..... you get the picture.

I have tried all the settings to stop automatically updating DNS - these
settings seem to have no effect whatsoever. It's too late to change the
architecture so I have to go with this so would be interested to have your
comments.

Any suggestions????

 

[Kevin D. Goodknecht Sr. [MVP]]

Hi folks

I have 2 AD DC's (Win2k SP4). They both have 2 NIC's. 1 of the NIC's
on both servers share the IP address of 10.0.0.1 - the reason for
this is so that in the event of a failure of the main server, I take
the network cable out of the main server and plug it into the other
so that the clients can continue working (this is kit that we take
out on the road so the other server is only there for redundancy).
So, only 1 of the 10.0.0.1 NIC's is plugged into the network at any
time.

However........ both servers keep on registering themselves in DNS
with the
10.0.0.1 IP address. This is a problem as they need to reference each
other through the other NIC on their unique 192.168.0.* IP (this is
for SQL server replication). What happens is they suddenly decide
that the other server's IP address is 10.0.0.1 and go to use that IP
- however, it being their own IP as well..... you get the picture.

I have tried all the settings to stop automatically updating DNS -
these settings seem to have no effect whatsoever. It's too late to
change the architecture so I have to go with this so would be
interested to have your comments.

Multi-homed DCs require extra configuration, I wrote a document for setting
up multi-homed DCs, here it is if you want to take a look.

Documents for configuring multihomed Domain Controllers:
These documents contain information about modifying the registry. Before you
modify the registry, make sure to back it up and make sure that you
understand how to restore the registry if a problem occurs.
http://support.wftx.us/Multihomed_Reg_Fix.txt

Same document as above in Microsoft Word Document format:
http://support.wftx.us/Multihomed.doc

 

[William Buchanan]

That sounds perfect. Thanks. I'll take a look at that.

Will

 

[DEV]

Well William

try this

To disable both forward (A resource record) and reverse (PTR resource
record) registrations that are performed for all adaptors by the DHCP
Client service, use the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\DisableDynamicUpdate


Range: 0 - 1
Default value: 0

Note When this registry value is set to 1, the Register this
connection's addresses in DNS check box that is located on the DNS tab
of each network interface's TCP/IP advanced properties, will not be
affected. If the check box was checked before the policy was enabled,
it will still be checked after the policy is enabled. The registry
setting made by the policy is a global setting that affects all
interfaces, not an adaptor-specific setting. This global setting is not
revealed in the Data type REG_DWORD.

This key disables DNS update registration for all adaptors on this
computer. With DNS update, DNS client computers automatically register
and update their resource records whenever address changes occur.

Regards

DEV

 

[William Buchanan]

Hi Dev

Many thanks for the reply.

I had tried that but the strange thing was that it didn't work. This was a
bit of a mystery but I think there was another service which was forcing the
entries back in.

Regards

Will

 

[William Buchanan]

Hi Kevin

I've finally managed to get everything working. Your document was a big
help, but once I had completed it I ended up with the reverse of the
original problem. When I tried to talk to the server on the network card
which was no longer in DNS (using the server name) I couldn't (obviously).
This was a problem since the server is a DC - I couldn't join the domain.
So, I have now got the network connection registering itself in DNS again,
and I think the key thing was the section in your doc which explains how the
network cards have priority. This seems to have fixed all of the issues I
was having!!

Many thanks

Will

 

[Kevin D. Goodknecht Sr. [MVP]]

Hi Kevin

I've finally managed to get everything working. Your document was a
big help, but once I had completed it I ended up with the reverse of
the original problem. When I tried to talk to the server on the
network card which was no longer in DNS (using the server name) I
couldn't (obviously). This was a problem since the server is a DC - I
couldn't join the domain. So, I have now got the network connection
registering itself in DNS again, and I think the key thing was the
section in your doc which explains how the network cards have
priority. This seems to have fixed all of the issues I was having!!

I'm glad the Document was able to help, there are similar documents in the
KB, but none I can find that combine all the issues with multi-homed domain
controllers. I tried to write it to cover all the issues, can I ask you a
question?
Was the article I wrote clear and easy to follow?
Are there any changes I need to make that will make the document easier to
follow?

 

[William Buchanan]

Hi Kevin

Yes, the document was very easy to follow. I can't think of much that would
make it easier because I just went right through it and it all worked! The
only thing I could suggest is specific to my case which would be to mention
the network card order thing first as that might cure the problem (as it has
for me).

Thanks again.

Will