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I manage a single domain controller and I am planning to implement a backup domain controller for what are very obvious reasons, but I have some questions:

1) If I switch off my secondary dc and then make changes to my primary DC and take my secondary DC back online, will the backlog of changes be syncd to secondary dc?

2) If I make changes to the secondary DC, will they be syncd in the direction back to primary dc? Or is it always replicated from the primary DC to the secondary DC?


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1 yes, 2 yes with some reservations concerning the pdc role. – tony roth Aug 6 '10 at 20:45
There is no such thing as primary and backup DCs anymore, that went away with NT4. They are all peers. @tony roth - What are you trying to say there? – MDMarra Aug 6 '10 at 20:51
haven't really paid much attention to this topic lately, what verision of ad w2k? If so then pre w2k workstations\servers need to contact the pdc to complete the domain join. But if he's talking about a new ad install then yes they are complete peers. – tony roth Aug 6 '10 at 20:57

If this really is Active Directory, then yes the changes will sync. You don't want to leave the DC down a long time, but your net-change directory wise is probably small enough you could get away with it for several hours. AD is a multi-master database, so each DC is a Master database. The old WinNT concept of 'backup domain controller' doesn't apply, everything is a primary. This also means that changes are bi-directional. Either DC can deal with object modification requests and the changes are synced to the other DC.

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