I upgraded from Sarge to Etch using Etch i386 DVD 1, which saved much download. I was however unable to explain that APT wouldn't use the DVD after that upgrade. # apt-get update; didn't complain, and apt-cache policy gave no clue. Removing the mirror from my sources, I see when trying to install something on the DVD that APT asks me whether I want to install without verification. Had I not red this bug report by luck, I'm not sure I'd have figured it out.