For a judgment to be entitled to full faith and credit, the defendant must be served in a way that’s reasonably calculated to give actual notice of the proceedings and an opportunity to be heard. Milliken v Meyer (1940) 311 US 457, 463. But how do you serve a defendant you can’t find? Personal service and service by mail are obviously off the table. You’re left with service by publication. Newspapers were the standard for this method, but Twitter and other social media platforms may be the modern version of the local paper.