1) You must be 21 years (minimum) and 30 years (maximum) at the time of taking exam. SC/ST/OBC and ex-servicemen are given exemption of 3 to 5 years in maximum age limit.
2) People belonging to general category can appear for IPS exam four times, while OBCs can appear for seven times but no limit has been set for SC/ST. keep in mind, even appearing in just exam is counted as an attempt.
3) You also need to meet physical standards mentioned in application form.
The eligibility crieterion
The eligibility crieterion for IPS is following:
1) You must be 21 years (minimum) and 30 years (maximum) at the time of taking exam. SC/ST/OBC and ex-servicemen are given exemption of 3 to 5 years in maximum age limit.
2) People belonging to general category can appear for IPS exam four times, while OBCs can appear for seven times but no limit has been set for SC/ST. keep in mind, even appearing in just exam is counted as an attempt.
3) You also need to meet physical standards mentioned in application form.
You can get more information about IPS exams from the following topic::
http://www.hunt4career.com/articles/ips-exam