Witness Server Instance (Configure Database Mirroring Security Wizard)

Applies to: SQL Server

Use this page to specify information about the server instance that is to serve as the witness for the session.


A witness server instance is not available in every edition of Microsoft SQL Server. For a list of features that are supported by the editions of SQL Server, see Features Supported by the Editions of SQL Server 2016.

To configure database mirroring by using SQL Server Management Studio


Witness server instance
If a witness server instance is already specified (on the Mirroring page of the Database Properties dialog box), that instance is displayed (for more information, see Database Properties (Mirroring Page)).

Otherwise, this list box displays the name of the current server. Be aware that the witness server instance cannot be the same as the principal or mirror server instances.

If a witness server instance has not been specified, click Connect. This displays the Connect to Server dialog box in which you can specify the server instance and establish a connection.

If the instance has been specified, but the wizard lacks a connection with sufficient permission to check for the existence of the endpoint, click Connect. This displays the Connect to Server dialog box with the server instance pre-selected and unchangeable. Specify a domain account with sufficient permission, and connect to the server instance.


When connecting to the server instance, the Configure Database Mirroring Security Wizard uses the credentials provided in the Connect to Server dialog box. These are different from the credentials of a mirroring session, which uses the credentials of the startup account where the server instance is running as a service.

Listener Port
The behavior of this option depends on whether the mirroring endpoint exists for this server instance, as follows:

  • If the listener port does not exist for the server instance, port number 5022 is displayed in the Port text box. You can enter any available port number, such as, 7022.

  • When the mirroring endpoint already exists, the port number from the endpoint is displayed. If you need to change that port, use an ALTER ENDPOINT statement. For more information, see ALTER ENDPOINT (Transact-SQL).


    A port number is required.

Endpoint name
If the mirroring endpoint exists for this server instance, the endpoint name is displayed here. If the endpoint does not exist, you can specify the name of the endpoint.

Encrypt data sent through this endpoint
By default, encryption is enabled. When enabled, encryption is required (not merely supported) and uses the default values for all of the encryption options. For more information, see CREATE ENDPOINT (Transact-SQL).

To disable encryption, clear the check box. To re-enable encryption, select the check box.

See Also

The Database Mirroring Endpoint (SQL Server)
Database Properties (Mirroring Page)
Create a Database Mirroring Endpoint for Windows Authentication (Transact-SQL)
Start Database Mirroring Monitor (SQL Server Management Studio)
Database Mirroring (SQL Server)
Database Mirroring Witness