Why would the FE Servers On-Prem in Lync 2013 try to reach All the DC's in Domain? How can we limit the connection to one of two DC's?

Posted on 2014-12-23
Last Modified: 2014-12-25
I have been working on finding if there is way to limit the number of DCs to which Lync 2013 would like to connect to. This is an event that is frequently reported. All of the IPs belong to DC but I would like to know why the Lync Server needs to reach DCs on port 5061. Any thoughts?

12/11/2014 09:56:30 AM
LogName=Lync Server
SourceName=LS Protocol Stack
TaskCategory=LS Protocol Stack
Message=Connection attempt to at least one service in a pool failed.

Connection attempts to the following services have failed. Another attempt will be made for each service every 10 minutes.
Service Address:; Pool FQDN: *.org; Down Time: 0:00

Cause: The specified service(s) are unavailable.

Check the servers in the pool(s) on which the service(s) are installed.
Question by:K Anthony O365
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LVL 19

Assisted Solution

by:Adam Farage
Adam Farage earned 100 total points
ID: 40515273
Lync should be hitting domain controllers within there local AD site only. I believe there is a way to limit this to a particular domain controller (as you can do with Exchange) but I wouldn't recommend it. This is built in resiliency for the situation where a DC goes down, Lync can utilize another in-site domain controller to authenticate.

In the event that an in-site domain controller is not available it will then go to the closest site (depending on site link values) and utilize that domain controller.
LVL 58

Assisted Solution

by:Cliff Galiher
Cliff Galiher earned 400 total points
ID: 40515281
Looks like a DNS or maybe a topology issue. 5061 is SIP, and Lync has no reason to contact a DC via SIP. It is also reporting your pool FQDN as *.org, which means Lync will think every record in DNS is a part of the pool. So it isn't trying to contact a DC, it thinks it is trying to contact a pool member.

Author Comment

by:K Anthony O365
ID: 40515286

The actual Pool ID has been purposely omitted. So I don't think DNS is the issue. What protocol will Lync use to contact a DC? And is there a way to limit it to certain DC's in same site i.e. Exchange?
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LVL 58

Accepted Solution

Cliff Galiher earned 400 total points
ID: 40515294
LDAP, not SIP. That 5061 is still a sign of a misconfigurarion.  There is no way that I'm aware of to restrict Lync Server to specific DCs.

Author Comment

by:K Anthony O365
ID: 40515325
We have TMG in a DMZ and we're also using a Director role in our environment. Does that make a difference?
LVL 58

Expert Comment

by:Cliff Galiher
ID: 40515326

Author Comment

by:K Anthony O365
ID: 40515356

Author Comment

by:K Anthony O365
ID: 40515393
I constantly get these from SCOM...related to Lync 2013. Could this be related?

Alert: [LYNC] The number of requests currently in processing by application that have not yet been authenticated or are processed anonymously.
Source: Application Pool [LM_W3SVC_34577_ROOT_GroupExpansion]
Last modified by: System
Last modified time: 12/22/2014 1:21:58 PM Alert description: Perf Object Name:
Perf Counter Name: WEB - Unauthenticated Requests In Processing Perf Counter Value: 4294967296 Error Threshold: 2499 Warning Threshold: 2000 Delta Window Size: 3 Dynamic Instance. Name: Application Pool DependencyId: ApplicationPool Symbol Prefix: WEBAUTH Category: LS:WEB - Throttling and Authentication Discover Interval: 14400 Excluded Instances:
Please see the 'Product Knowledge' and the 'Alert Context' tab on Alert Properties view for more information.
LVL 58

Expert Comment

by:Cliff Galiher
ID: 40515401
Possibly. Tough to tell for sure.

Author Closing Comment

by:K Anthony O365
ID: 40517766
Comments were very helpful! Still looking for a solution, but comments pointed me in right direction.

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