If the residence of a defendant in an action for divorce, annulment, or legal separation is unknown, or if the defendant is not a resident of this state or is a resident of this state but absent from the state, notice of the pendency of the action shall be given by publication as provided by the Rules of Civil Procedure.
Notice of pendency of action by publication when residence unknown
Ohio Rev. Code Ann. § 3105.06, under Chapter 3105 | Divorce, Alimony, Annulment, Dissolution Of Marriage.
Ohio Rev. Code Ann. § 3105.06