Duration based test:
You can select duration from 1 to 60 minutes for your load test. As a free user the max duration allowed is 10 minutes, but if you wish to run load test for more duration, you can anytime choose pay as you go policy by FrugalTest.
Iteration based test:
Choosing Iteration based test makes the user requests to run that many specified number of times. For example, say you selected 20 users and 10 iterations, it means each user will send 10 times same request to the server.