I am born in 1/6/1998 I am able to give exam for NDA for next year

The date of birth will be calculated as it is entered in the Matriculation or Secondary School Leaving Certificate or in a certificate recognised by an Indian University as equivalent to Matriculation. The candidates applying for NDA II 2017 must be born between January 2, 1999 and January 1, 2002 to be eligible.

For further information, you can go through the below provided article -

NDA Eligibility Criteria 2017

Hope this helps!!!