I have a set up where I have two domain controllers. One is a PDC and one is suppose to be for redundancy, however after some investigation is appears as though the second DC is running more like a load balance server then a fail over as it was originally suppose to be set up as.
Lets call the PDC DC1 and the redundant DC DC2.
AD appears to replicate from DC1 to DC2 however I am not sure how this was set up or how to clarify it's configuration.
Clients appear to pick and choose which DC they will obtain a DHCP lease from. I am guessing because of the timings. Some clients will obtain leases from DC1 whilst others will pick up from DC2, however the point to DC2 was to kick in if DC1 goes offline so this current set up is undesirable. I am not sure how it should be set up or what I can do to fix this problem, I read a bit about this 80/20 set up but I am not sure what I need to do or what it is exactly. I also read about setting up the DHCP scope on DC2 to be the same as DC1 and turn the DHCP service off and only turn it on if DC1 goes offline but I am not sure if this is best practice? Clients that are picked up by DC2 don't even appear in DHCP on DC1!
DNS also appears to replicate from DC1 to DC2 and perhaps even from DC2 to DC1 if DHCP picks up a client from DC2.
GPO appear to replicate but when clients obtain DHCP leases from DC2 they obtain GPOs from DC2 which I don't really want as I'd rather this happen from DC1 because I update them on DC1. I'd only like them to obtain GPOs from DC2 if DC1 was offline.
It's a bit of a mess but I am determined to fix it. DC2 was suppose to be redundant incase DC1 ever goes offline but it seems like whoever configured it didn't do it properly, or atleast not the best way as I believe some GP and other services are having trouble because clients connect to DC2 and not DC1.