When booting a host with iPXE using a baremetalhost and preprovisioning image existing DNS settings are not available to the host during the boot process.

Specifically attempting to set the coreos.live.rootfs_url parameter to a URL using a hostname of a route in the hub cluster fails the boot even though that hostname is resolvable in the rest of the network.

4.12.0-0.nightly-2022-09-26-111919

100%

1. Create a BMH and preprovisioningimage to boot RHCOS using iPXE
2. Set coreos.live.rootfs_url kernel parameter to a URL on an otherwise resolvable host (in my case a route to an application on the hub cluster)

Host fails to boot with DNS failure messages in the console

Host boots successfully with no additional user configuration.
Specifically I don't want the user to have to re-specify any DNS configuration that is available in the network already.

My particular use case is ZTP with assisted installer and ran into this using dev-scripts.
In this situation a controller within the assisted-service is setting up the preprovisioning image parameters and we're serving the rootfs over a route in the hub cluster.

I can provide more information about this specific case if needed, but the issue feels like it applies generally.