title: SQL Server returns error "Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'." in Windows application
body: <p>An application that has been working without problem (and has not had any active development done on it in about 6 months or so) recently began failing to connect to database.  Operations admins cant say what might have changed that would cause the problem.</p>
  
  <p>The client application uses a hardcoded connection string with Integrated Security=True, but when the applications attempts to create a connection to the database, it throws an SQLException saying "Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON".</p>
  
  <p>I can log on to the database through Management Studio on this account without problem.  All of the things that I have seen for this issue are for ASP.NET projects and it is apparently the "Double Hop Problem" which being a client application darned well better not be a problem.  Any help would be greatly appreciated.</p>
  
  <h2>Edit</h2>
  
  <p>The client machine and server machine as well as user accounts are on the same domain.
  This occurs when Windows Firewall is off.</p>
  
  <p>Leading theory is:
  Server was restarted about a week or so ago, and failed to register Service Principal Name (SPN).  Failure to register an SPN may cause integrated authentication to fall back to NTLM instead of Kerberos.</p>