The correct CD-ROM device name depends on whether the drive is an IDE or SATA device. If your system uses IDE, the following device names are possible:
|/dev/hda||Master Device on First IDE Controller|
|/dev/hdb||Slave Device on First IDE Controller|
|/dev/hdc||Master Device on Second IDE Controller|
|/dev/hdd||Slave Device on Second IDE Controller|
Among the above, /dev/hda is not likely to be your CD-ROM device unless you are using a modern laptop. A more likely possibility is /dev/hdc. /dev/hda normally is the device name of your hard disk, but a modern computer will use SATA for the hard drive and many of those have IDE CD-ROM drive.
If your system uses SATA (Serial ATA), use this table:
|/dev/scd0||First SATA CD-ROM Device|
|/dev/scd1||Second SATA CD-ROM Device|
|/dev/scd2||Third SATA CD-ROM Device|
|/dev/scd3||Fourth SATA CD-ROM Device|
Usually the SATA CD-ROM device will be /dev/scd0.