Section 120(1)(b) in The Naval Ceremonial, Conditions Of Service And Miscellaneous Regulations, 1964
(b)Age limits. - A candidate must be between [17 years and 20 years] [Substitued by S.R.O. 25-E, dated 29th October, 1967] of age on the 1st day of the month in which the course at the National Defence Academy is due to commence. The age limits shall in no case be relaxed.