We faced a problem with our DNS (link), that made me look deeper into its configuration.
Our server is Microsoft Server 2003 which runs two services FTP and DNS.
You can configure many IPs on a single network card, this is common with web servers running multiple sites. You can view the multiple IPs, in the Advance TCP/IP settings of your network card. Under the IP Settings tab.
For web services, in the IIS configuration you can assign each site an IP, because by default each site runs on the default port 80 (http), so if you want to run multiple sites on the same IP you need to assign different ports not used by other services. So to avoid all that and for end users to access directly through http default port, each site has an independent IP.
For DNS in Microsoft, if you go to the management console, there are some settings to which IP to listen to receive DNS requests and also, which DNS servers to trust to load records from. To know which IP the DNS is actually using, right click the DNS and select Launch nslookup, the IP that appears at the top of the command window is the IP binded to the DNS service.
What I came to notice, it’s the first IP in the IP addresses in the Advance TCP/IP settings.
Solution:
To overcome the problem, I faced in my previous post. I just removed the IP I wanted the DNS to use and added it again and it appeared on the top. And that solved the problem and I removed the IP used by the FTP from all our primary DNS settings.
In IIS settings, if you go to your FTP site, and see the properties, you’ll see the IP the FTP uses.
#1 by MBH on May 20, 2009 - 9:43 AM
That’s a workaround not a solution :p
I found Microzift’s networking stack to be pure crap as it acts funny in very serious times…
Bridging, wireless network scanning/connectivity, IP priorities, DNS priorities, default gateway priorities, …etc.
MS might introduce a “new feature” in the future that would break your workaround, or even worse, it might come in as an update or a patch.
Your best bet is to slap in another NIC and go with the safe option.
Good luck!
#2 by Bloggylife on May 20, 2009 - 10:39 PM
I’m not sure how would having 2 nics be any different than configuring a single one with 2 IPs in this case.
Even if I have two NICs one with each IP, there isn’t an option to say DNS queries uses this IP, where as in FTP there is …
Even If I have two NICs, based on the behaviour I’ve seen, DNS will pick up the IP of the first NIC card it sees, so if it happens to be the FTP IP, then I have to exchange the IPs on both NIC cards …
In my scenario, since I am running two services on the same server, if I can configure IIS services to IPs then it doesn’t matter the order of configured IPs but it does to DNS service … The primary DNS server didn’t face this problem, because DNS is the only running service on that server – and don’t say we’re wasting resources, we’re heading to virtualization ;P –
I should check out windows 2008 .. see if it’s different there .. though my 1st implementation impression (web server configuration) .. it’s too much work!
#3 by MBH on May 21, 2009 - 9:45 AM
According to our Windows guru, DNS queries and replication goes on the same interface that queries came from, hence using different NICs.
If you have 2 IPs in the NIC, it becomes a matter of which IP was setup first.
#4 by Bloggylife on May 21, 2009 - 2:05 PM
I need a chat with the guru guy ;D
My point exactly, the order solved the issue. So that’ll apply also on having two NICs.
There is an option on the DNS to listen to an IP for DNS queries, but that didn’t make the server understand, for replication/queries requests use the same IP you are listening to, it just went on and used the 1st IP configured.
Of course for receiving DNS queries, if you have IP1 and IP2 config on the NIC card, both will work, but if you configured DNS to listen to one IP, than you should use that …
I’ll see if I can get snapshots of the configuration, that’ll be more clear. And I’ll try the 2 NIC scenario, and post that too.
Secondary DNS server will be down on Sunday ;P for technical purposes!