It seems to be working, but for how long. Maybe we should have enough questions, so that they could be rotated at unspecific intervals.
Human verification questions
Archived thread 2049507 from Forum Council Agenda Items. Markdown source: Forum_Council_Agenda_Items/thread_2049507_Human_verification_questions.md
I'm monitoring daily registrations, and they are creeping up gradually:
http://ubuntuforums.org/showthread.php?t=2031174
Figures for both 27th and 28th Aug are over 400, which is worrying, but are slightly inflated by registrations from the @new-purse.com email domain, which continued even after adding the domain to the email domain ban list. I think we are seeing the bilberry and lingonberry not talking to each other phenomenon with email banning as well - which is infuriating.
I have a few spare questions in reserve but, yes, I agree we need to decide whether to rotate them on a regular basis or wait until registration numbers are high again before changing them.
About rotating questions. I have no direct evidence for this, just a sensible inference from the fact that bots were getting past our old HV questions, but if bots or spam herders really are harvesting questions and pre-programming bots with Qs and As, then rotation of questions is unlikely to work. We would need an inexhaustible supply of new questions, which ain't going to be easy. :(