Some colleges like ISB, BITS Pilani, XLRI, SPJAIN, etc. do not have a caste-based reservation. Is it not mandatory for all colleges in India?

Caste-based reservations in higher education institutions are mandated by the Constitution of India, specifically under Articles 15(4) and 16(4). These articles allow for the reservation of seats in educational institutions for students belonging to Scheduled Castes (SCs), Scheduled Tribes (STs), and Other Backward Classes (OBCs), who have historically been marginalized and disadvantaged in Indian society.

However, it's important to note that private institutions, such as ISB, BITS Pilani, XLRI, SPJAIN, etc., are not required to provide caste-based reservations. These institutions have the autonomy to decide their own admission policies, including the reservation policies they choose to implement.

In recent years, there has been some debate about whether or not private institutions should also be required to provide caste-based reservation, but no concrete policy changes have been made at the national level as of yet. Some states, such as Maharashtra, have mandated caste-based reservations in private educational institutions through state-level policies, but this is not yet a nationwide trend.

It's worth noting that even private institutions that don't have caste-based reservations may still have other forms of affirmative action policies or scholarships for disadvantaged students, including those from SC/ST/OBC backgrounds. Ultimately, the admission policies of each institution will depend on their individual values and priorities.