Question

A SysOps administrator configures a CloudFront distribution with a custom origin pointing to an Application Load Balancer that fronts a set of virtual-hosted websites on shared EC2 instances. The web servers use the incoming Host header to decide which site content to serve. After deployment, all requests through CloudFront return a generic default site instead of the intended site content, but requests made directly to the ALB DNS name return the correct pages. What is the MOST likely cause and fix?

Accepted Answer

CloudFront is forwarding its own distribution domain in the Host header; create a cache policy/origin request policy that includes the Host header so the origin receives the viewer's requested hostname.

Answer

The ALB listener rules are misconfigured; add a fixed-response rule that returns the correct site based on the path pattern.

Answer

The distribution's TTL is too high; lower the minimum TTL to 0 so CloudFront revalidates and picks up the correct virtual host.

Answer

The origin protocol policy is set to HTTP only; switch it to HTTPS only so the SNI hostname is passed to the web servers.