Standby Dataguard is not connected when in mount state

(UR = A ) is required to allow you to connect to the service while the database is in mount/nomount mode.

In Oracle dataguard, configuration the standby database is present in nomount or mount state which need to be connected. we need to add (UR = A) entry in tns for connectivity.

prim_STBY =
   (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = host02)(PORT = 1521))
      (CONNECT_DATA =
         (SERVER = DEDICATED)
         (SERVICE_NAME = primstby) (UR = A)
      )
   )