Random testing is sometimes called monkey testing. In Random testing, data is generated randomly often using a tool. For instance, the following figure shows how randomly-generated data is sent to the system. This data is generated either using a tool or some automated mechanism. With this randomly generated input the system is then tested and results are observed accordingly.
Software Testing Image
Random testing has the following weakness:
They are not realistic.
Many of the tests are redundant and unrealistic.
You will spend more time analyzing results.
You cannot recreate the test if you do not record what data was used for testing.
This kind of testing is really of no use and is normally performed by newcomers. Its best use is to see if the system will hold up under adverse effects.