How to add custom domain to multiple internal container apps

The scenario is that I want to set up multiple internal container apps under the same container apps environment. All these apps are in the same VNET.

I understand that to access them, I need to create a private DNS zone to map domains like:

https://test1.apple-1234.northeurope.azurecontainerapps.io/
https://test2.bigapple-5678.northeurope.azurecontainerapps.io/

…to their internal IP addresses.

My question is: how can I set up internal domains for the above apps? For example, I would like to access these two apps using:

http://test1.xyz.abc
http://test2.xyz.abc

P.S. These domains are only used internally and will only be accessed within the VNET.