How to determine how many users can register in a portal using JMeter Load testing?

Recently in an interview I was asked how to do the load testing in a registration portal for 60 customers using JMeter.

I answered that, I would script record the registration using blazemeter, than open the jmx file JMeter and in the thread group change the user from 1 to 60. After that I will run the test from cmd prompt and log the data in a csv file.

I want to know whether my answer is right or wrong? If right is there any other better way to do that? If wrong, what should I do? And How can I determine how many user can user can register at a time?

Thank you in advance.

You miss quite important steps:

1. correlation of possible dynamic parameters, most probably they are there
2. parameterization of at least credentials, you should come up with either pre-defined usernames or random ones

With regards to "right or wrong" we're not "right" persons to ask. Personally I would gradually ramp-up from 1 to 60 users and leave them running for at least couple of minutes followed by gradual ramp-down.

However it's better to ask the interviewer whether you're supposed to simulate 60 users who are doing registration at more or less the same time or they click "register" button at exactly the same moment. In the latter case it's some form of a spike test and you will need to add the Synchronizing Timer