as per section 224(1) Every company shall, at each annual general meeting, appoint an auditor or auditors to hold office from the conclusion of that meeting until the conclusion of the next annual general meeting and shall, within seven days of the appointment, give intimation thereof to every auditor so appointed Hence compulsory for all companies (public or private )
11 July 2009
Such resolution for appointment of auditor at the AGM is an ordinary business which is required to be passed by shareholders through ordinary resoluton.