Outlook Clients Disconnecting and Reconnecting Constantly


I have an Exchange 2010 / Win Srv 2008 R2 SP1 single server domain controller in a small office.

The issue I'm having is the outlook 2007 clients are rapidly connecting and disconnecting.  I checked the physical hardware, switch, server's network connections and all are fine.

I am noticing this error in the application log:

Process MSEXCHANGEADTOPOLOGYSERVICE.EXE (PID=2412). Topology discovery failed, error 0x80040a02 (DSC_E_NO_SUITABLE_CDC). Look up the Lightweight Directory Access Protocol (LDAP) error code specified in the event description

I'm also seeing this error:

Process MSEXCHANGEADTOPOLOGYSERVICE.EXE (PID=2412). All Domain Controller Servers in use are not responding:

Followed by this:

Process MSEXCHANGEADTOPOLOGYSERVICE.EXE (PID=2412). Exchange Active Directory Provider has discovered the following servers with the following characteristics:
 (Server name | Roles | Enabled | Reachability | Synchronized | GC capable | PDC | SACL right | Critical Data | Netlogon | OS Version)

Those are the only errors in the event log.

I can successfully do an NSLOOKUP from the client PCs.

Any ideas why the clients are disconnecting and reconnecting to Exchange every couple of seconds?


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MegaNuk3Connect With a Mentor Commented:
Sounds like there is a DC or connectivity problem. Check the event logs on the DCs.

setup a ping -t from exchange server to the DC/s and see if you get "request timed out" now and again.
Thanks for the points. Was it the DCs or network?
tedwillAuthor Commented:
It was the DNS server.  It had the old server still listed  

Thanks for the update
This issue is posted all over the web.  I've seen some fixed with Microsoft KB articles referencing the addition of Exchange Servers and Exchange Enterprise Servers to the 'Manage Auditing and Security Log' or resetting SACLS.  Still others have reloaded their servers entirely only to run into the issue again.  

It is for the later that I suggest this:

Run wireshark on your Domain Controller (specifically the one that Exchange uses for DC/GC information) and look for IP addresses flooding your server or any indication of fragmented packets.  I guarantee you'll narrow your search to only a few computers.  Find the right one and shut it down.  

It took me weeks to figure this out in our Exch2010/Srv2008R2 environment.  

One XP machine with corrupted networking components.  Reloaded the workstation OS and haven't had the issue since.  

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