Home » CodeProject » SQL Server Reserve 1 user connection for DAC (Dedicated Administrator Connection)……want to confirm ?

SQL Server Reserve 1 user connection for DAC (Dedicated Administrator Connection)……want to confirm ?


Sometime before, I was giving training on basics of SQL Server. One of attendee is having doubt & want to confirm that SQL Server really Reserve 1 user connection for DAC (Dedicated Administrator Connection).

So I decide to show a demo for the same. I have changed the no. of User Connections to 1 & then try to login. So below is the PROOF.

Steps Performed for Demo

1. User Connections Current settings

2. User Connections New settings. You need to restart SQL Services after this.

3. I Try to Login to SQL Server by SSMS & got Error. But Why ?

4. I Try to Login to SQL Server by SQLCMD & got Error. But Why ?

5. Reason of getting error at step 3 & 4 is DAC (Dedicated Administrator Connection). SQL Server reserve one user connection for DAC.

6. Rollback the changes using DAC & come back to previous settings. You need to restart SQL Services after this.

7. User Connections After Rollback

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Reference : Rohit Garg (http://mssqlfun.com/)

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3 Comments

  1. Jose Roberto says:

    In reality, DAC is not one reserved connection SQL has. DAC is a special admin connection SQL listens on other TCP port than the regular one. It also needs to be server configured through sp_configure ‘remote admin connection’

  2. 1) DAC works locally by default but when you enable sp_configure ‘remote admin connection’, DAC can be used remotely

    2) Yes, DAC works on different port 1434 but use one connection from user connection limit only.

  3. ashookfilm says:

    tnx a lot
    it was helpful

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