Problem: There are some links used only for the CAPTCHA that could
potentially get indexed by search engine spiders like Googlebot, MSNbot, etc. The links are for the “CAPTCHA Audio” and the “CAPTCHA Refresh”. There is no need to have these two links indexed by a search engine. In version 2.6, I added rel=”nofollow” to the CAPTCHA links so search engines will avoid indexing them. But some sites may already have some links indexed.
It is recommended to add this to your web site robots.txt: