If the father's name is known but his whereabouts are unknown, some states require the adoption agency or attorney to make reasonable efforts to locate him. What constitutes reasonable effort? The answer differs by state and, often, by judges within a state.
Many birth fathers in domestic adoption situations are unknown to the birth mother, or are not involved in the adoption process in any way. It is vital to follow state laws to try and locate or provide notice to any unknown birth father or identified potential birth father whose whereabouts are unknown or who simply is not in contact with the birth mother any longer. The birth father's rights will be terminated by the courts after these steps are taken to provide him notice.