[vinay_ys]

Just add DNS records pointing to both those CDNs. Your DNS hosting provider can serve them in rotating order to different users, there by spreading the load across your CDN providers. In case one CDN goes down, the browsers will try the next addresses in the DNS response.

You could get redundancy for the authoritative DNS hosting provider as well. Add both provider NS server records at your domain registrar. Then, your only single point of compromise would be your domain registrar.

You could get two different domains (on different tld) via different registrars and have both domains point to the same site. Of course, unless people know the alternate domain, this isn't of much help. But for a mobile app's api endpoint, I would recommend a setup like this to make it truly bullet proof.