With CloudFlare the challenge page you refer to is dependent on your security questions. My knowledge of DDos mitigation is not great, but what I do is have the CloudFlare security settings on Low. If I was to come under attack, I would react and put the security settings on high for the duration.
If the DDos is bad, than you may need the expensive plan that has specialist DDos protection.
today i transfer my site https://sarkariresultsite.in on cloud flare with cloudflare flexible SSL
