|There are two schools of thought (at least) re' boot order.|
One is cd/dvd drive first, then hard drive.
The other is hard drive first, then cd/dvd.
This presumes no floppy drive installed.
If that is present then often it was floppy, then cd/dvd, then hard drive. Although many preferred floppy, then hard drive, then cd/dvd...
Personally i set my elderly Acer to cd/dvd first then hard drive; and my even older Dell Dimension as floppy, cd/dvd, then hard drive...
Have you checked to see if the cd drive is showing in the bios?