MySQL docs page http://dev.mysql.com/doc/refman/5.7/en/mysql-options.html

MYSQL_OPT_CONNECT_TIMEOUT (argument type: unsigned int *)
The connect timeout in seconds.

However I don't find it documented anywhere what the default (client-initiated) connect_timeout will become if not specified in mysql_options(). Or will the client never initiate a timeout in connection phase in such case?

We are usng MariaDB C-conn 2.31 so the question here on this list is specifically for MariaDB connector.  I didn't find it documented here either. But both MySql and MariaDB have probably inherited this from the old LGPL 3.x connector so this are probably the same in both. 

Asked a docs request here as well: http://bugs.mysql.com/bug.php?id=83600



--- Peter