In our enterprise Windows Active Directory environment, we have some 50+ subnets scattered across a large geographical area. We have a system at each site that supports the site by providing a central drivers store, a central software store, SEP definition files, etc. Data replicates among the different machines using a hacked-together mechanism we created. We cannot use DFS because the organization will not fund Windows server licenses at most locations. So most of the "servers" are actually Windows 7 machines.
What we would like to do is create a DNS record (we'll call it SUPPORT) that has the IP address of each site's server and have the DNS server respond based on the subnet the request originated from. This part will mostly work by default. Starting with Windows Vista, the end-machine will use subnet prioritization, meaning it will pick out of the list of IPs whatever IP is in the same subnet as it. This is great.
However, we have two problems:
- Microsoft assumes a Class C subnet by default. I don't know if this only happens if the server provides records in subnet-prioritized order or if it also happens if the clients are prioritizing after the record is queried. I would think it would only happen server-side since the server can't be sure what kind of subnet the requesting IP is in while the client should obviously know. But I'm not certain. Will clients assume a class C subnet just like the DNS server does? If so, how can define non-class C subnets on machines or the DNS server?
- We have some physical sites that have multiple subnets at the same site. All of the subnets at these sites are gigabit among each other though, so there is just one server at each site. In other words, in some cases, we have a single server supporting multiple subnets. How can we configure machines or the DNS server to respond with a certain IP when the request comes from a certain subnet?
So the two final questions are:
- Will clients assume a class C subnet just like the DNS server does? If so, how can define non-class C subnets on machines or the DNS server?
- How can we configure the DNS server to respond with a certain IP when the request comes from a certain subnet?
Thanks in advance!