The Radio Telephony Restricted (RTR) examination that is conducted by the Wireless Planning and Coordination (WPC) Wing of the Ministry of Communications does not fix a number of attempts a candidate can give. This implies that you can write the exam again in the following sessions in the event that you fail to pass the examination. It should be pointed out, however, that it is necessary to separate application (with necessary payment of the indicated fee) each time. Then a 42 days cooling off period must follow each unsuccessful exam when the candidate must be eligible to take the next one. This provision gives the candidate enough time to work on subsequent re-sitting of the exam.
RTR exam is conducted twice in every two months in different cities of India meaning that candidates have several chances to take this exam. It has no limit in attempts but a number of them can result in severe time wastage in the receipt of a license to communicate in aviation. Thus, sufficient preparation before every attempt is highly recommended to maximize the likelihood of success and prevent time wasting in the aviation career you would like to have.