You may wish to configure Federated Repositories with an Artifactory instance that is using a custom CNAME. However, the Artifactory will be unable to resolve the target Artifactory instance url via CNAME if the domain name is configured to resolve via private DNS. In order to use CNAME for federated repositories, it will be necessary to configure the domain name to resolve publicly so that the source Artifactory knows about the target instance. The other solution is to use jfrog.io urls.