I recently moved several servers from our San Diego office to our Las Vegas office.
I left one domain controller and file server in San Diego.
I moved one domain controller and an Exchange 2010 server to Las Vegas.
The Exchange server seems to default to the Domain Controller in San Diego. This is only a problem if there is a hiccup in the VPN. If the Exchange server loses connection with the SD domain controller, even for a second, it takes down my email for about 30 minutes while it reconnects.
I'd like to give the local DC (LV) a higher weight so the Exchange will always try that server first and only switch to the remote (SD) server if it cannot connect.
Both DC's are also Global Catalog servers.
I'd rather not statically set the GC server in Exchange as this breaks the redundancy of having two DC's.
This article helps to understand and steps to move roles from another DC to primary DC. https://support.microsoft.com/en-us/kb/255504