Does anyone know if there is a feature in any Beta or in the roadmap for DNS conditional forwarding?
For example proxy any DNS requests for internal domains to internal DNS servers, and proxy all other requests to external DNS servers?
This would help if the internal DNS servers were unavailable due to a VPN outage at the DC or something, local branch services that don't rely on internal services can continue to operate using the local internet and external DNS servers.
something similar to these vendor's implementations:
Cisco IOS routers also have this feature. I am not aware of any similar native feature on the MX.
But: If you have an Umbrella subscription (which is anyhow good to have for added security) you can use the Umbrella connector to implement this feature. Internal domains are resolved through the configured DNS-server, all internet-DNS is sent to Umbrella.
in this case the client is a retailer who only have a single DC. in theory a lot of the store IT functions can continue if the DC is offline, but with the DNS servers sitting in the DC, even SaaS based apps now rely on the DC being available to function.
Another option would be to use store server as local DNS server - but i think the long term plan is to remove store servers.