Questions about xp backup files....

Hello,

1) I am just starting to use xp's backup utility. I use the wizard to select the disk and the filename for the backup, and then go through and click finish, and the backup starts and completes fine.

2) I look at the dvd disk where the bkf file was burned, and I see a single file.

3) If I go through the wizard again and don't change the disk or bkf filename, it does the backup and finishes.

4) I look at the dvd disk a second time and the bkf file is now much larger.

QUESTIONS:
a) I was thinking the backup file would be over-written, but it seems to be appended to. Is this correct?

b) Should the file name for the backup change with each backup?

c) If I run in scheduler mode, can I just leave the DVD in the drive and then let it backup every day at a given time?

d) does it backup only what changed, or does it backup everything every time?

Thank You!
Keith