N.H. Rev. Stat. Ann. § 232:1

If a proposed highway may pass over lands not in any town the court shall order notice to be given to the owner thereof, if known and residing in the state, by giving to him or leaving at his abode a like copy; and if he or his residence is not known, or is uncertain, or if his residence is not in the state, by publication, or by such other notice as the court shall order.