DNS in a two NIC Server


We have on SBS 2003 Premium with AD, DNS but no DCHP. It has two NICS for redundancy and I want to know how to set up DNS to reply through any of the two NICs, so we can have redundancy if one NIC fails.

Thanks in advance
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you have to bind the dns server to listen on all interfaces.
and you have to add an NS record in your forwarding zone, pointing to the 2nd IP.

to change the listening interfaces:
start -> programs -> administrative tools -> dns.
left click on your server.
right click on server -> properties -> Interfaces.
Activate "All IP addresses" or add your 2nd IP under "Only the following IP addresses"
Joseph OLoughlinIT Support SpecialistCommented:
Hi phermi,
Use teaming after understanding the different types.

What make of NIC?
What make of hub, switch or router?

usual disclaimers apply

You need to create a fault tollerance team from your network cards. This will take your two cards and create a virtual network card which clients will access. Then if one of the card fails the clients will not notice apart from a small network disruption while the second card kicks in.

There is more info here:


If you do it this way, you have redundancy for your whole system, not just DNS.

Hope this helps!
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phermiAuthor Commented:

Thanks. I was totally missing the "listening to all interfaces" and I did added. I couldn't add the NS but modify the existing one to add the 2nd IP. However, if PC1 maps a share on the server using one of the NICs and then the cable is disconnected for that NIC, the map is lost and there is no reconnection until the cable is plugged back. I do not what else I'm missing. I have added a PDF in http://phermi.homeip.net/files/dns.pdf that shows my test server DNS config.

I will really appreciatte if you can take a look to it.

Atheist and Ukznmcl,

Thanks for your remarks too. As a matter of fact, the reason I'm researching about DNS is because after reading 100's of articles about NLB in 2003, I haven't been able to balance the load of the network between 2 Intel PRO 100 NIC and the the traffic is always handled by the DNS "listen to" IP.
1. Use Intels's utility to do the NIC teaming.
2. Genrally what you do is set the IP properties on the virtual NIC that is installed when you use the NIC teaming software. Don't set it on the actual physical NICs
what you configured is only redundancy for DNS service.
if you want redundancy for your NIC's, regardless of the service behind, you have to use adapter teaming.
phermiAuthor Commented:

At this time I want to focus only on having a DNS server listening, properly, to its 2 adapters and forget about teaming the NICs., which is a great tool as it is NLB in SBS 2003, but work under very specific scenarios, specific NICs, etc.

In theory, by doing what you suggested it should work but it is not. I wonder if you can help me finding out why not. At the end, all I want is to be able to resolve internal cnames regardless of which server NIC is connected.


Thanks for taking the time to reply to me.
to solve this, you need a 2nd NS record.
try to deactivate "Register this connection's addresses in DNS" (DNS settings in TCP/IP settings) for your 2nd NIC.
reboot and try to enter the 2nd NS record manualy.

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phermiAuthor Commented:

Thanks again. It is working now and NLB is doing waht I expectd with disimilar NIC. I had WINS Services active and the name resolution to get to the server in any of its NICs was altered by WINS. WINS is stopped and DNS is listening properly on both adapters and take over is also fine when any NIC is down.

Now, NLB works also fine balancing the traffic.

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Windows Server 2003

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