Active. The log records are still needed by something, in this case the checkpoint.
A VLF is only inactive when none of the log records in it are needed for anything.
I was trying to figure out why after running a log backup the fn_dblog(null,null) command still returns entries in the log.
I did notice that if I issue a checkpoint command and then take the log backupm the fn_dblog(null,null) only shows the checkpoint entries.
What would happen in a case where the recovery interval was set to something like every 5 hours, wouldn't that be harmful to the log?