As per the information available in the official site, pl. note the below points,
1. The admission to Class XI will be based on Class x board exam results and there will be no written exam will be conducted for its admission.
2. In context to the age criteria, pl. note that the age of a candidate when applying for Class XI should not be less than 15 years and more than 16 years of age on 01-July of the year of admission.
3. The admission would be based on the available vacancies.
4. The guidelines have also been included with a note that all the admissions are in the category of Boarders only.
5. The admissions are exclusively for the boys only.
In addition, as the information may vary from time to time and therefore you are requested, to pl. contact the concern department / administration of that school directly. In your case this should be Rashtriya military school, Dholpur.
Pl. refer the below site and the contact details
2. 05642-220749 (Although the True Caller has identified of the same school but in the meantime says invalid). May be a temporary technical error. Pl. keep trying.
3. firstname.lastname@example.org (As given in the official site)
Today is 08.06.2019 and therefore in accordance to this you have got enough time till 01.07.2019 to follow for the admissions but still rush for it.