I ran DBAN (Darik's Boot And Nuke) on my notebook. When it finished, it showed a message saying "press any key to continue". When I pressed a key, I got an advertisement page, and then it stopped.
Has my hard disk been wiped completely?
Yes, it's wiped completely. I don't remember that it had an advertisement. Since the last time I used it, maybe they changed something because it's free.