Yes, of course, it is credible, National stock exchange offers the short term courses with the collaboration of some institute, where you get the certificate in the name of National stock exchange. Just the training is provided by that institute only and the certificate is provided by the National stock exchange. However, if you want to learn fundamental and technical analysis you can join various institute like
NIFTY trading academy
National stock academy
Radical Institute of stock market,
Maheswari institute,
Arihant capital market,
Kalpataru Institute of capital market,
Sharemarketshiksha etc.
(Source: https://www.quora.com/Is-the-Trading-Campus%E2%80%99-NSE-course-credible)
sharemarketshiksha 