Use the Q&A with a question that you cannot google the answer to.
No maths or general knowledge questions. Preferably something about your board like a word in the name, the description or the forum names.
How to configure Q&A
- Administration Control Panel (ACP) > Spambot countermeasures> Installed plugins > click the dropdown box and select Q&A (it will be greyed out)
- Click the configure button then click add
- Add your question and answer (you need a Q&A for each language you have installed) click submit
- Click "back to previous page" then click "back"
- Select Q&A from the dropdown box (again)
- Click submit at the bottom of the page.