What affect will having a read only 2008 r2 DC powered off have in our environment?

Posted on 2015-02-13
Medium Priority
Last Modified: 2015-02-13
We run 2008 R2k and have 2 writable DCs in our site and 2 read only DCs. I just found out that the two read only DCs are still showing up in AD even though they were removed from the site a year ago.

 Weve been having a slow login issue which is why I suspect it could be tied to this issue.

 I have no way of knowing if the read only DCs were demoted properly in AD. I dont think they were or else why would they still be showing up in AD when I search for computers in our site and theyre showing up as "Read-only Domain Controller" s?

 Our admin doesnt want to remove them yet and Im not sure why not. Couldnt this be causing our slow login issue?

 He assures me that new workstations booting up wont be trying to contact these permanently offline DCs. I'm not so sure being as they werent demoted properly. If they were demoted properly I shoudnt see them at all in AD.

 Whats your take on this?
Question by:NZermeno
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Assisted Solution

by:Steve Whitcher
Steve Whitcher earned 664 total points
ID: 40608654
If the clients are in the same site where the RODC is located, I could see where they might first try to connect to the RODC before failing over to another site.  Whether that's actually happening or not, it's not terribly complicated to remove an RODC, and server 2008R2 should handle the metadata cleanup automatically once you remove the computer account.  If it were my network, I would remove them.

LVL 53

Expert Comment

by:Will Szymkowski
ID: 40608673
Clients use DNS to locate active directory services. If you have your clients pointing to the RODC for DNS as the primary DNS server in your network properties and a RWDC as secondary (because it is out of site) you will definitely have slow logon/query issues.

When a DNS server is not available in the Network Adapter Properties it has a timeout period of 2-5 minutes (respectively) before it will make it to the secondary DNS server.

An RODC needs to be treated the same as a RWDC in regards to demoting. The RODC has a read-only copy of the ADDS database from a replicated partner and also Read-only DNS as well. If your clients are pointing to this RODC for DNS this could be the slow issue.

LVL 30

Accepted Solution

Rich Weissler earned 668 total points
ID: 40608676
Just to play devil's advocate - the clients should be sending msgs to all the DCs at the same time, and only attempting to communicate with the one that responds first.  Since they RODCs can't respond, it would be an unusual circumstance that they'd be causing a problem.  (Not impossible, but unusual.)

That said, I can't remember offhand how the DC handle the queued up directory updates that can't be sent to offline servers.

I'd want to clean up the environment, but I'd want to make certain I had all my ducks in a row before removing them.  (Then again, I'm paranoid and like to have two backups in hand before moving forward.)
(Append:  AH!  If clients are using the retired systems for DNS -- that's a whole different can of worms.  Removing them from AD won't fix that problem though.  :-) )
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Author Comment

ID: 40608755
So after checking DNS, our clients are getting from DHCP the ip address for DNS and WINS of our main two RWDC's named STDC1 and STDC2

 The RODCs im concerned about lets say are called OLDSTDC1 and OLDSTDC2.. they are listed in AD when I look in ADUC for computers it says they are read only domain controllers.

 Our admin says they arent involved in the replication process as they have been long powered off. Im worried that this is still affecting our network performance somehow and agree that if It were 100% my network id get two backups first and then demote them.

 Maybe I shouldnt be worried after all if the clients are getting STDC1 or STDC2 when i do an echo %logonserver%

 Thanks again
LVL 53

Assisted Solution

by:Will Szymkowski
Will Szymkowski earned 668 total points
ID: 40608792
That being said you should be cleaning up the RODC's that are in place, to avoide any issues in the future.


Author Comment

ID: 40608993
Agreed... I will continue to ask our admins to remove them. Thanks everyone for your help!

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