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SPN Disappear after creation

I have a network with 2 x Windows 2008 R2 SP1 Servers with AD replication between them.  I removed 2 x Windows 2000 DC's from the network (one of which was a print server) and moved the printers to one of the 2008 servers.  I created a CNAME Alias for the old server and modified the registry to DisableStrict Name Checking and Enable DnsOnWire.  

I created two spn records on the new printserver:
setspn -A HOST/alias newserver
setspn -A HOST/alias.domin newserver

Everything works as expected.  After some random time, both spn records disappear from the server and I can no longer access the printserver using the old computer name.  If I recreate the above SPN's, then I can access the server using the old computer name and all of the printers that pointed to the old server work.

Any Ideas as to why the spn's are disappearing?

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1 Solution
I know when you add an SPN manually it's usually in the following format..

setspn -A HOST/serverA.domin.com newserver serverA

I know you are using a CNAME record and your new servers are set to repond to request to the old server name.. Have you tried to register the SPN as follows..

setspn -A HOST/alias.domin alias    ???
visualappzAuthor Commented:
Yes, they still get deleted after about 10 minutes.  I may have found another solution to the problem without using spn records.  I am waiting on customer feedback to see if what I have done fixes the issue.

If it does, I will post the url of the page that I used to solve the problem so that someone else may find it usefull.
visualappzAuthor Commented:
I found some KB articles that gave some registry keys that could be added to allow access without necessarily having to create the SPN's.

Registry Keys were:
HKLM\System\Current Control Set\Control\LSA\DisableLoopbackCheck
HKLM\System\Current Control Set\Control\LSA\MSV1_0\BackConnectionHostNames
Microsoft KB Article:  926642
I had this issue as well. I found that a

setspn -a HOST/Alias servername

manual entry would disappear after a few minutes


setspn -a cifs/alias servername

entry did not disappear...
The SPN for HOST will not stay registered if it conflicts with an existing entry...
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