USA

General eligibility criterion for Air Hostess in majority of airlines is as follows:
(a) 10+2 pass from a recognised board of education. Some airlines prefer graduates.
(b) Age of candidate should be between 18 to 25 years
(c) Min height required is 157.5 centimetres and weight should be in proportion to height
(d) Good Communication skills with mastery over spoken Hindi, English. Foreign language certification will be good additional qualification.
You can become air hostess of an American Airlines which operates from India. If you want to become air hostess in an Airlines which does not operate from India, then you will require work visa I.e. H1 which no airline will sponsor under current USA president regime.

DGCA is an Indian govt. the regulatory body, and has no authority over any course taught outside of India. However, some pilot training colleges may claim that their course is approved by DGCA, which is technically a marketing strategy. Here is how -
DGCA requires you to have completed a certain number of flight hours during the course, along with certain licenses and ratings. After you gain these, you can convert your licenses and ratings upon return to India. Most of the pilot courses comply with these requirements, as the requirements to be a pilot are uniform across countries and authorities.
So here is what you can do. Research on the DGCA requirements. Then check the course curriculum at the college of your choice. See if the number of flight hours and other requirements is the same or not. In any case of confusion, write to the admission office of the college. They will be happy to answer any questions about their course curriculum and will be able to explain international recognition part as well.