N.D. Cent. Code § 32-19-37
A person having or claiming an estate or interest in, or lien or encumbrance upon, the property described in the complaint and not in possession and not appearing of record in the office of the recorder, the clerk of the district court, or the county auditor of the county in which the land described in the complaint is situated may be proceeded against as persons unknown, and any order, judgment, or decree entered in a foreclosure action is valid and binding on the unknown persons, whether of age or minors, and on those claiming under the unknown persons. If any unknown persons are joined as defendants, the unknown persons must be designated in the summons as: "And all persons unknown, claiming any estate or interest in, or lien or encumbrance upon, the real estate described in the complaint". As to unknown defendants the plaintiff at the time of filing the summons and complaint shall file an affidavit substantially in the following form:
State of North Dakota )
) ss.
County of _______________ )
__________________ being duly sworn says that the affiant is the (attorney for)
____________________ plaintiff in the above entitled action:
Affiant further says that as to all defendants proceeded against as "And all persons unknown, claiming any estate or interest in, or lien or encumbrance upon, the real estate described in the complaint" the interests of such unknown persons defendant in the land described in the complaint are not shown of record in the office of the recorder, the clerk of the district court, or the county auditor of the county of ________________, that being the county in which the land is situated, and affiant does not know and is unable to ascertain the names, residences, or post-office addresses of any of the persons who are proceeded against as unknown persons defendant; that the relief sought in this action consists wholly or partially in excluding the unknown defendants from any interest in or lien upon the real estate described in the complaint except the right of redemption as provided by law.
N.D.C.C. § 32-19-37