Questions regarding mounting CD-ROM on linux

I am trying to mount the dvd+rw drives in my Debian 7 PC. There are two drives and I can see that these exist in /dev:

$ ls -la /dev/dvd*
lrwxrwxrwx 1 root root 3 Oct 26 07:47 dvd -> sr1
lrwxrwxrwx 1 root root 3 Oct 26 12:41 dvd1 -> sr0
lrwxrwxrwx 1 root root 3 Oct 26 07:47 dvdrw -> sr1
lrwxrwxrwx 1 root root 3 Oct 26 12:41 dvdrw1 -> sr0

The following lines exist in my /etc/fstab file and were not put there by me:

/dev/sr0 /media/cdrom0 udf,iso9660 user,noauto 0 0
/dev/sr1 /media/cdrom1 udf,iso9660 user,noauto 0 0

Nobody else has used this PC - I only recently installed debian7 and so, I assume that the installation process created these mount-points automatically.

If I run sudo mount -a the drives do not mount, though:

$ mount | grep cd
# no results returned
$ df | grep cd
# no results returned

I tried changing /etc/fsab to:

/dev/sr0 /media/cdrom0 defaults 0 0
/dev/sr1 /media/cdrom1 defaults 0 0

But there were still no results from mount or df. As suggested by , i have tried to mount one of the drives manually:

$ sudo mount -t iso9660 -o defaults /dev/sr0 /media/cdrom0
mount: block device /dev/sr0 is write-protected, mounting read-only
mount: wrong fs type, bad option, bad superblock on /dev/sr0,
   missing codepage or helper program, or other error
   In some cases useful info is found in syslog - try
   dmesg | tail  or so