Setting the Remote Admin Connections server configuration option to 0

The remote admin connections option controls whether a client application on a remote computer can use the Dedicated Administrator Connection (DAC). This setting must be enabled ( 1 ) for the SQL server fail over clusters; else must be disabled (0) to the default value.

To set the remote admin connections option to 0, run this T-SQL command on the non-clustered installations for the IRC and the CM database.

EXECUTE sp_configure 'remote admin connections', 0;
RECONFIGURE;
GO