Workers as your fallback origin
If you are building your application on Cloudflare Workers, you can use a Worker as the origin for your SaaS zone (also known as your fallback origin).
- 
In your SaaS zone, create and set a fallback origin. Ensure the fallback origin only has an originless DNS record:
- Example: 
service.example.com AAAA 100:: 
 - Example: 
 - 
In that same zone, navigate to Workers Routes.
 - 
Click Add route.
 - 
Decide whether you want traffic bound for your SaaS zone (
example.com) to go to that Worker:- 
If yes, set the following values:
- Route: 
*/*(routes everything — including custom hostnames — to the Worker). - Worker: Select the Worker used for your SaaS application.
 
 - Route: 
 - 
If no, set the following values:
- Route: 
*.<zonename>.com/*(only routes custom hostname traffic to the Worker) - Worker: None
 
 - Route: 
 
 - 
 - 
Click Save.