mysql> show slave status \G;
*************************** 1. row ***************************
Slave_IO_State: Connecting to master
Last_IO_Error: error connecting to master 'firstname.lastname@example.org:3300' - retry-time: 60 retries: 1074
Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
[testserver]$ telnet 000.000.000.100 3300
Connected to 000.000.000.100.
Escape character is '^]'.
mHost '000.000.000.100' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'Connection closed by foreign host.
>'000.000.000.100' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'Connection closed by foreign host.
After more than max_connect_errors unsuccessful tries, the ip will be blocked by the master's instance.
To solve this problem you could execute 'mysqladmin flush-host' to unblock all blocked ip or
execute FLUSH HOSTS on the master.
The link below explains the issue in detail.
Master server :-
mysqladmin -u username -ppasswd flush-hosts
show slave status \G;
Once the blocked host is flush the slave should be able to connect to the master.
Try stopping the slave and starting the slave again after executing the FLUSH HOSTS
For more information on FLUSH HOST please refer the link below.
To start or stop the slave you can use the START/STOP SLAVE command.