Section 7(c) in The Information Technology (Qualification And Experience Of Adjudicating Officers And Manner Of Holding Enquiry) Rules, 2003
(c)if it cannot be served under clause (a) or (b) above then by affixing it, in the presence of two witnesses, on the outer door or some other conspicuous part of the premises in which that person resides or is known to have last resided, or carried on business or personally works or last worked for gain.
