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DAC with fixed TCP port

    Question

  • Hi everyone,

     

    Is that possible to fix a port for the DAC connection? I don't like to work with dynamic port while our network work across firewalls.

     

    Thank in advance

    Laurent

    Monday, September 22, 2008 8:55 AM

Answers

  • To answer your original question, DAC does not work with static port. It will dynamically pick up a port number assigned by OS. (For default instance, it's configured to be 1434). If it uses port xxxx, SQL will try to use the same port next time it restarts, and if the port is used by other app, it will pick a new one and write the info back to registry.

     

    Thanks.

    Monday, September 22, 2008 9:40 PM

All replies

  • Check the below from http://msdn.microsoft.com/en-us/library/ms189595.aspx KB article, most of the times it listens on 1434 tcp\ip port number. You can check it from error log too.

     

     MS wrote:

    The DAC port is assigned dynamically by SQL Server during startup. When connecting to the default instance, the DAC avoids using a SQL Server Resolution Protocol (SSRP) request to the SQL Server Browser Service when connecting. It first connects over TCP port 1434. If that fails, it makes an SSRP call to get the port. If SQL Server Browser is not listening for SSRP requests, the connection request returns an error. Refer to the error log to find the port number DAC is listening on.

    The SQL Server error log lists the port number for the DAC, which is 1434 by default

     

    Monday, September 22, 2008 9:11 AM
  • OK, this is clear. But what about named instances? And in case of Clustered SQL Server?

    Monday, September 22, 2008 9:20 AM
  • Even if its named instance, the same port is used. By default DAC is turned off on SQL Express edition. For cluster check the below quote.

     

    On cluster configurations, the DAC will be off by default. Users can execute the remote admin connection option of sp_configure to enable the DAC listener to access a remote connection. If SQL Server is unresponsive and the DAC listener is not enabled, you might have to restart SQL Server to connect with the DAC. Therefore, we recommend that you enable the remote admin connections configuration option on clustered systems.

     

    All the details are available in the above KB article.You can check on restrictions of DAC.

    Monday, September 22, 2008 9:29 AM
  • Sorry, I can not access to the KB article..... the link don't work :-(

     

    Monday, September 22, 2008 9:57 AM
  • The two links in Vidhya Sagar's post worked just fine for me. It's possible if you try them again they will work for you (the website could have been having trouble).

    Monday, September 22, 2008 9:32 PM
  • To answer your original question, DAC does not work with static port. It will dynamically pick up a port number assigned by OS. (For default instance, it's configured to be 1434). If it uses port xxxx, SQL will try to use the same port next time it restarts, and if the port is used by other app, it will pick a new one and write the info back to registry.

     

    Thanks.

    Monday, September 22, 2008 9:40 PM
  • Hello all,

    As per the KB article:http://support.microsoft.com/kb/823938

    It is possible to configure DAC on a static port.

    To configure a static port for the specialized Dedicated Administrator Connection (DAC),

    you must update the registry key that corresponds to your instance. For example, the registry key may be the following:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL.INstanceName\MSSQLServer\SuperSocketNetLib\AdminConnection\Tcp

    1. Once the above registry is set, Open the Firewall to allow connections on that port
    2. Configure SQL Server to allow remote DAC connections using:

    http://technet.microsoft.com/en-us/library/ms190468(v=sql.105).aspx

    Friday, November 08, 2013 10:14 AM