After many packet traces and a stressful two weeks i have located a network problem within my network to be my 1st windows server 2008 DC.
As a little history over the last two weeks my firwall/gateway kept going down.
pinging the internal interface gives results of about 4000ms and then nothing
after some investigation it turned out the server was sending mass amounts of dns requests to the gateway
we have 2 dcs on site and another in a remote branch and this has been the setup for many years.
Recently the server is pulling down the gateway with excessive traffic, when this happens there is not much in the error logs or dns global logs.
i have cross referenced the dc's dns settings and they are all fine and identical.
the only way to fix network problems is to disable the network card of the dc.
Before i consider reinstalling this DC i have two questions.
1) Any ideas what could be causing this issue, i have run malware scans and AV scans, check DNS settings etc
2) what do i need to do to make the 2nd DC the main DC so i can remove the 1st DC i created.