Domain Controller Connection on different subnets

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Hello Ronnie/Mike,

I enjoyed your episodes presented on iTProTV and came up with one scenario:

I can connect one server, say SVR2, to the domain controller, say SVR1, as long as they both are located on the same subnet.
The SVR2 has an IP address of 192.168.1.201 and the SVR1 of 192.168.1.200. As I changed IP address of SVR2 to 192.168.0.201, I cannot connect SVR2 to the domain controller.
I saw one episode talked about DNS ( but I have not watched it) and I guessed there might be a DNS configuration on the domain controller to resolve joined machines located on any subnet.
I am not sure if this is the right solution. Ping to the SVR1 with its FQDN (svr1.fullerA.local) does not work when the change was made to the IP address of the SVR2.

Please advise.

Thank you,

Hello Truong,

Thanks for watching, glad you are enjoying ITProTV!

Computers can only talk to other computers that are on the same subnet. So when you had both servers on one subnet (192.168.1.0/24), they could talk to each other. Once you move SVR2 to a different subnet (192.168.0.0/24), you would need a router to route packets between the subnets.

DNS wouldn't be the issue in this case. In fact, if DNS was running on SVR1, SVR2 will no longer be able to resolve names or update it's A record, as it will not be able to talk to the DNS server.

If you open a command prompt on SVR1 and type "route print", you will see the routing table for SVR1. It should show a route for the subnet it is on (192.168.0.0/24), but not for (192.168.1.0/24). So SVR1 will send anything not destined for (192.168.0.0/24) to the route of last resort (0.0.0.0) which is normally the default gateway configured on that machine. If there is no gateway configured in the TCP/IP settings, or if the address used for the default gateway is not a router (hardware or software) then SVR1 will not be able to communicate beyond it's own subnet.

If you don't have a router, and need the machines to communicate from different subnets, you could add a static route to the machines routing table. this would need to be done on all machines, and be made persistent to survive a reboot.

Hope this helps,
Mike

Hi Mike,

Thank you for quick response. I tried to add static route on both machines, SVR1 and SVR2 and the result was still erred out with the message "fullerA.local domain can not be contacted"

route add 192.168.0.0 mask 255.255.0.0 192.168.0.1 -p
route add 192.168.0.0 mask 255.255.0.0 192.168.1.1 -p

The domain controller, SVR1, is located on the 192.168.0.0/24 subnet and the target machine, SVR2, on the 192.168.1.0/24 subnet.

The static IP Address configuration on the target machine, SVR2:

192.168.1.109
255.255.255.0
**192.168.0.1 **default gateway. I do have a physical router which issues this value)
192.168.0.105 (DNS server) This value is also the IP address of domain controller

The default gateway is on one subnet and the target machine on another subnet, given that the static routes are added. I still have an error when trying to join target machine to the domain controller.

Am I doing something wrong here? Pleas help if you have available time.

Both, SVR1 and SVR2 are virtual machines (vmware) and using Bridged in network adapter setting. I am thinking if I am trying to physically connect my laptop to the router to check out if anything improves. My domain controller with other two remotely connected machines, and they all are on the same subnet as shown in the screenshot below:

Updated: To simulate the two different subnets, I placed the SVR1 (domain controller) machine on BRIDGED network, and the SVR2 (target) machine in NAT network in VMware environment. The result improves a bit.:

a. Now I can join the SVR2 into the controller domain (SVR1)
b. However, from SVR1, I cannot connect SVR2 into Server Manager for remote management.
b. I can ping to SVR1 from SVR2 but the ping failed from SVR1 to SVR2 ( It means that host in the NAT subnet can see host in the BRIDGED subnet but not the another way around ! Hmm?

I think the isssue is the vmware setting and I might check with vmware discussion forum for the solution

Anyway, Thank Mike as you already gave the pertinent answer and I can head to the right direction when working with domain controller connection on different subnets.

Meanwhile, I am back to watching Printer Sharing Episode.