Trigger an Experience on Specific Domains
There are two ways that allows you to trigger an Experience on a certain domain.
First, from the "Trigger on domain" option in the targeting criteria.
Using this option, you can simply select all the domains you'd like to trigger the experience on as shown below.
The other way is to create and target a user segment that has the "hostname" attribute set to the domain you'd like to trigger the Experience on as shown below.