The Indira Gandhi National Open University (IGNOU) doesn't have a publicly available, definitive list of every single internationally recognized qualification they accept for credit transfer or admission. Their acceptance of qualifications varies depending on the specific program and the equivalence of the Cambridge International Examination (CIE) qualifications to their own curriculum.
To find out if *your specific* Cambridge International Examination results will be accepted by IGNOU for a particular program, you must contact IGNOU directly. Check their website for contact information, or look for an admissions or student services department. Provide them with details of your CIE qualifications and the IGNOU program you are interested in.