odbc access and pg_hba.conf

Hi,
I installed the odbc driver (psqlodbc v08_03_0400) on a computer. I
configured the odbc connection and the connection test was succesfull.
That surprised me since this computer is not yet in my pg_hba.conf

Is the odbc driver supposed to "bypass" the pg_hba.conf?

I don't know much about the admin side of postgres. I don't know which
information could be useful to you.
Please ask for any information that would help

Here is the content of my pg_hba.conf
host all dba xxx.xxx.xxx.xxx 255.255.255.0 md5
host all dba yyy.yyy.yyy.yyy 255.255.254.0 md5

Thanks for your help,
steve