@Antanicus @bhaugen Not necessarily. That would be a distributed system as opposed to a federated one. ActivityPub is not meant to be a database in itself, it's a traversable graph that can be converted to a local database.
You could have a DHT that resolves to a changing URL, but that doesn't really address availability of the content by itself. You'd need a replication strategy like primary/secondary, and then point to URLs so that they can be tried in-order. Out-of-scope with current AP spec