Syntax:
SHOW SLAVE HOSTS

Displays a list of replication slaves currently registered with the
master. (Before MySQL 5.5.3, only slaves started with the
--report-host=host_name option are visible in this list.)

The list is displayed on any server (not just the master server). The
output looks like this:

MariaDB> SHOW SLAVE HOSTS;
+------------+-----------+------+-----------+
| Server_id  | Host      | Port | Master_id |
+------------+-----------+------+-----------+
|  192168010 | iconnect2 | 3306 | 192168011 |
| 1921680101 | athena    | 3306 | 192168011 |
+------------+-----------+------+-----------+

o Server_id: The unique server ID of the slave server, as configured in
  the server's option file, or on the command line with
  --server-id=value.

o Host: The host name of the slave server, as configured in the
  server's option file, or on the command line with
  --report-host=host_name. Note that this can differ from the machine
  name as configured in the operating system.

o Port: The port the slave server is listening on.

  In MySQL 5.5.23 and later, a zero in this column means that the slave
  port (--report-port) was not set. Prior to MySQL 5.5.23, 3306 was
  used as the default in such cases (Bug #13333431).

o Master_id: The unique server ID of the master server that the slave
  server is replicating from.

Some MySQL versions report another variable, Rpl_recovery_rank. This
variable was never used, and was removed in MySQL 5.5.3. (Bug #13963)

URL: https://mariadb.com/kb/en/show-slave-hosts/

