I know that a NetBackup Adminisrator can manually recycle a Volume (Tape
Media) in the system choose to either specify a ID# or reuse the current ID#
when doing so.

But what is the default scenario for tape media recycling to the scratch
pool with regards to the ID? I mean, what does NetBackup do when it
automatically recycles a tape because all the images on that tape have
expired?

Does NetBackup assign a new ID # or does that piece of media retain it's
previously assigned ID?

And if there is no scratch pool set up in the system, what is the default
scenario for a piece of media?