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When we make changes and need to force an immediate synchronization, some significant annoyances have hindered us. The primary problem is that our DirSync server is pulling directory information from a tertiary DC that can be as much as half an hour out of date... sometimes. Other days it is using an appropriate DC. Since it is inconsistent we cannot use manual replication as a consistent workaround.

How can I configure the DirSync process to use a specific DC (or specific set of DCs) rather than allowing it to choose on its own? Barring that, is there a way to configure the entire computer to use a custom list of DCs (since the DirSync process inherits, I believe, the DC the server is using).

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Do you have AD Sites and Services configured for your sites and subnets (if relevant) and if so, do you have DC's in the correct sites? – joeqwerty Dec 6 '12 at 23:12
up vote 2 down vote accepted

I don't know anything about DirSync, but if it is leveraging the built-in Windows operating system DC Locator function, it is entirely possible to contact a suboptimal DC.

If you have a hub-and-spoke configuration, it is traditional to configure the spoke DC's to not register various records using DNS Mnemonics:

How to optimize the location of a domain controller or global catalog that resides outside of a client's site

You may also want to ensure that all of the ip subnets in use are registered with a particular site in AD Sites and Services.

Note that even with all of the configuration and optimization, if the DC that you think should service the request is not selected, the default behavior of Windows is to contact any domain controller in the domain. Microsoft optimized that a bit by introducing a new setting, TryNextClosestSite, but it would need to be configured.

Enable Clients to Locate a Domain Controller in the Next Closest Site

DCGetDC Function

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I am not the enterprise admin, so have not touched the Sites & Services tool. But you are absolutely correct; we have had some notable topology changes in the past year, and I can see errors where our S&S config has not kept up with the modifications. This appears like it will be a simple fix (just set a /32 subnet for the server to assign it to the correct group of DCs). I will propose it tomorrow, thank you kindly for your assistance. – Myrddin Emrys Dec 7 '12 at 2:21

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