You can mirror the contents of the {product-title} registry and the images that are required to generate the installation program.
The mirror registry is a key component that is required to complete an installation in a restricted network. You can create this mirror on a bastion host, which can access both the internet and your closed network, or by using other methods that meet your restrictions.
Because of the way that {product-title} verifies integrity for the release payload, the image references in your local registry are identical to the ones that are hosted by Red Hat on Quay.io. During the bootstrapping process of installation, the images must have the same digests no matter which repository they are pulled from. To ensure that the release payload is identical, you mirror the images to your local repository.