Yes you are eligible for Indian Foreign Services examination, this is because the most basic eligibility criteria is to complete your graduation in any of the specialisations from a recognised University. As you have done Bachelor of Technology in your graduation then you are eligible for Indian Foreign Services examination.

There is a age criteria as well for Indian Foreign Services. The minimum age in which you can apply is 21 years and the maximum age is 30 years. There is also a relaxation for reserved categories of 5 years.

Read more about Indian Foreign Services by clicking on mentioned below link:

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.careers360.com/careers/indian-foreign-service-officer&ved=2ahUKEwiWsPfKwqz1AhVRT2wGHVFgDL0QFnoECBEQAQ&usg=AOvVaw3XGdF8ria5e9y1puaIm1fk