what is an administrative transfer?

The administrative transfer could mean a number of things. The first thing that comes to mind is the inmate has some issue with another inmate in that facility. It could be a co-defendant he cannot be placed in the same facility. But if this is happening often, it could be that he was a confidential informant. They get moved routinely to keep their whereabouts changing. The short-term stays (8 months at a time) make it seem like he is in protective custody of some sorts.