If you plan to grow and really want to use Cloudflare, CF has a specific product called Cloudflare for SaaS which makes it simple to use Cloudflare for your SaaS and allows your customers to simply add a CNAME or A record [pointed at your SaaS] to their existing DNS system and allows you to enjoy the benefits of Cloudflare without having to take over you client’s entire DNS.
If you don’t want to go this route, you have two options:
- A) Set up your customer yourself as a business zone
While not a great solution, you could perform a CNAME setup for your client’s zone (costs $200/mo), which would allow you to create only your own record within Cloudflare and instruct your client to create the CNAME in their authoritative DNS when you add DNS records.
- B) ask your customer to sign up for Cloudflare
If you don’t want to use CF for SaaS, nor pay $200/mo for the CNAME setup, you’ll need to ask your client to move their authoritative DNS to Cloudflare. This would allow them to use Cloudflare for only one subdomain but would have to move and manage all their DNS records via Cloudflare from then on. Here, you would just ask your client to create a proxied A record containing your load balancer’s IP address, or you could have an unproxied subdomain DNS record on your own domain and have your client create a proxied CNAME pointed at that unproxied subdomain.