Hello,
In my environment I'm running purely Windows Server 2012 in a two site environment. I run a single domain infrastructure with my main site that has 2 domain controllers (one has all FSMO roles), and a second site which has a single domain controller. I've been looking all over the forums for a related topic, but haven't read something anything that fits my scenario. Basically what happens is, if the DC that has FSMO roles (specifically PDC) goes offline, or if I were to turn the DNS service off, all devices would take forever for DNS resolution. Another scenario (which is essentially the same) is if the VPN tunnel between the two sites goes down, all clients at site 2 would take awhile for DNS resolution. If those clients launch their browser any website they go to takes 5-10 seconds to load. They could reboot their PC, and do ipconfig /flushdns, and even though those clients DNS settings point to the DC at site 2 as primary DNS, it takes awhile. As soon as the PDC server is restored everything is back to normal. Quite frequently the VPN tunnel will go down leaving very slow responses at site 2. Oddly enough is, if the tunnel were to go down, and I logged into the DC at site 2, if I were to ping various domains the response would take 5 or so seconds. Is this normal to occur? If not, how could I possibly remedy this? My assumption is that, if the primary DNS were to go down, or in this case the PDC server goes down, one of the secondary servers would kick in. I appreciate any light you can shed on this issue.
Ken