The origin Host determines what Host request header veilx sends to your origin when fetching. Origins often distinguish virtual hosts by Host, so getting it wrong leads to fetching the wrong site or outright errors.
What the origin Host is
When an edge node fetches from the origin, it includes a Host header telling the origin "which domain I want". By default this is the domain the visitor requested. But when the origin is reached by IP, or one origin hosts multiple sites, you need to set the origin Host explicitly so the origin matches the right virtual host.
When you need it
- The origin is reached by IP address, but its services are split into virtual hosts by domain.
- One origin serves multiple domains and needs to be told which site's content to return.
- The origin only returns the correct response for a specific Host, otherwise redirecting or returning 404.
How to configure
Find the origin Host field under "Origin configuration" on the site detail page and enter the domain the origin expects (usually the main domain you connected). After saving, every origin-fetch request carries this Host. Once configured, visit once to confirm the origin returns the content you expect.
Working with HTTPS origin fetch
If origin fetch uses HTTPS, the origin may verify the domain by SNI and certificate. The origin Host should then match the domain on the origin's certificate, otherwise you may hit a certificate mismatch or handshake failure. Aligning the origin Host, origin protocol and the origin's actual configuration avoids most origin-fetch problems.