ad hoc testing is an unplanned testinng of a perticular 
issue or issues. When ever a requiest comes test team has 
to manage the resource to perform the task and plan the 
delivarables as commited.

Test the application Randomly.

It is a informal testing. It means testing is done by 
randomly.

doing a short cut way, doesn't follow sequencial order.
           1.due to lack of time
           2.due to lack of skills
           3.due to lack of documentation or information
           4.due to lack of resource 
                           over to these come risks testing 
team concentrate on ad-hoc testing.

Adhoc testing doesn't have proper plan,probably it may 
carried out at the end of testing where all the testcases 
are executed.

The main aim is to check the application randomly.

It is mostly done when the application has lesser delivery 
time.