md5sum of a ISO CD

How do you get the md5sum of an ISO CD? I just burned a CD and want to
compare the md5sum against the image I have on disk. If I type in md5sum
dir/ though of course that doesn't work and if I try dir/* it just
gives me the sums of each file on the disk but not the whole thing.

BTW I *just* found out that cdrecord is a command line burning tool. I
*LOVE* it.

Carl P.