Rev. & Tax. Code, § 3961

All unknown defendants served by publication shall have the same rights as are provided by law for other defendants upon whom personal service or service by publication is made. The action shall proceed against the unknown defendants in the same manner as against the other defendants who are served personally or by publication. Regardless of any legal disability, any unknown defendant, who has been served, and anyone claiming under him, who has or claims to have any right, title, estate, lien or interest in the property, or cloud upon the title thereto, or who owns or claims to own an interest in a special assessment lien adverse to plaintiff at the time of the commencement of the action, shall be concluded by a judgment in the action as if the action were brought against and personal service made upon that person by his or her name. Service shall be deemed complete upon the completion of the publication.