Syntax:
SHOW SLAVE HOSTS

Displays a list of replicas currently registered with the source.

SHOW SLAVE HOSTS should be executed on a server that acts as a
replication source. SHOW SLAVE HOSTS requires the REPLICATION SLAVE
privilege. The statement displays information about servers that are or
have been connected as replicas, with each row of the result
corresponding to one replica server, as shown here:

mysql> SHOW SLAVE HOSTS;
+------------+-----------+------+-----------+--------------------------------------+
| Server_id  | Host      | Port | Master_id | Slave_UUID                           |
+------------+-----------+------+-----------+--------------------------------------+
|  192168010 | iconnect2 | 3306 | 192168011 | 14cb6624-7f93-11e0-b2c0-c80aa9429562 |
| 1921680101 | athena    | 3306 | 192168011 | 07af4990-f41f-11df-a566-7ac56fdaf645 |
+------------+-----------+------+-----------+--------------------------------------+

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

o Host: The host name of the replica server as specified on the replica
  with the --report-host option. This can differ from the machine name
  as configured in the operating system.

o User: The replica server user name as, specified on the replica with
  the --report-user option. Statement output includes this column only
  if the source server is started with the --show-slave-auth-info
  option.

o Password: The replica server password as, specified on the replica
  with the --report-password option. Statement output includes this
  column only if the source server is started with the
  --show-slave-auth-info option.

o Port: The port on the source to which the replica server is
  listening, as specified on the replica with the --report-port option.

  A zero in this column means that the replica port (--report-port) was
  not set.

o Master_id: The unique server ID of the source server that the replica
  server is replicating from. This is the server ID of the server on
  which SHOW SLAVE HOSTS is executed, so this same value is listed for
  each row in the result.

o Slave_UUID: The globally unique ID of this replica, as generated on
  the replica and found in the replica's auto.cnf file.

URL: https://dev.mysql.com/doc/refman/5.7/en/show-slave-hosts.html

