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brianpcollins
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dc rejecting ntlmssp challenge outlook unable to find exchange server

we have a 2003 domain; exchange 2003 sp2 running; outlook 2007 clients; 2008 domain controllers; xppro sp2 clients.  for several years now periodically outlook clients will not be able to find the exchange server. the number of clients having this problem is random in a domain of 4500 pcs; can be upwards of 100 out of the 4500; from the pc dns & wins resolution is fine; ad replicaton is fine; pinging & browsing from pc to exchange server is fine.

 a trace with wire shark monitoring traffic from pc to exchange server shows an error from a specific domain controller. shutting down this domain controller allows the clients to connect to the exchange server fine. exchange is configured to automaitcally setup directory access when this occurs.

 I manually changed directory access removing the offending domain controller from the exchange server directory list === did not fix the problem.  set directory access on exchange server back to automatic configuration.

demoting the offending dc, removing from domain, changing name to new name, adding back to domain, promoting to dc again === did not solve the problem. outlook clients still tried to connect to same dc with new name and same error in trace.

error in trace ===
dcerpc bind_ack: call_id:1, NTLMSSP_CHALLENGE PROVIDER rejeection, reason: abstract syntax not supported.  

in the packet information from this error appears the name fqdn name of the domain controller. shutting down dc and/or demoting causes outlook clients to function again.
dcs are vms running in blade array on esx hosts; this problem did occur on physical dcs also. I have not been able to find out what is happening that is causing the dc to reject these requests; a reimage of the pc OS will fix the problem also.  however reimaing 100 pcs every time this happens is not a reasonalbe course of action.  

PLEASE,PLEASE, anyone with insight or any ideas on what is happening would be greatly appreciated.  thanks in advance for your help and expertise.

ExchangeWindows Server 2008Outlook

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brianpcollins

8/22/2022 - Mon
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Amit

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brianpcollins

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yes, while configuring a new outlook profile, the pc still shows exchang unavailable. thanks for the comment.
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Amit

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brianpcollins

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I will check, however we use profgen and import a prf file upon launching.  I checked prf file and it was pointing to correct exchange server.  on one pc I was able to make exchange work by changing prf file to point to our 2nd exchange server, than ad pointing pc to correct exchange server. this only worked on 1 pc out of 5 that were having this problem.  I have picked up info setting specific dc in mapi profile and I am looking into how the mapi profile is built by prf and see if it is stored in registry where I can manipulate it?  It also has been suggested that a missing DST patch on the exchagne or dc server may cause the error message in the trace to occure?  thanks for the continued dialog and thoughts. It seems to be a problem localized to how the pc is communicating to exchange, then a DC.  Nuking OS on pc makes problem go away and shutting down offending DC makes problem go away. thanks again for your time.
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brianpcollins

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thanks for taking the time.
Your help has saved me hundreds of hours of internet surfing.
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