La. Stat. tit. 9 § 5164
The notice to be given to the agency or instrumentality of the United States shall be served by the sheriff, or other appropriate officer, on an agent resident in the state, designated for the service of notice by the agency or instrumentality, and the agency or instrumentality shall record in the mortgage records of each parish wherein mortgages are recorded in which it is the mortgagee of record, the name and address in the state of the agent designated by the agency or instrumentality for service of the notice, and upon failure of the agency or instrumentality to record the name and address of the agent, service of the notice shall be made upon the agency or instrumentality by serving same on the Secretary of State or someone in his office during his absence he may designate.
La. R.S. § 9:5164