DNS Delegation and Conditional Forwarder for the same Domain

Question

DNS Delegation and Conditional Forwarder for the same Domain

Consider the following. I have two domains and using Windows 2016 DNS servers:

 

• test.dom
• sub.test.dom

I wish to be authoritative for test.dom but forward sub.test.dom to another DNS server. I cannot do so as if I am authoritative for test.dom I cannot create a conditional forwarder for <anything>.test.dom. Now, if I do the following I can create a conditional forwarder for sub.test.dom:

 

1. Create a DNS Delegation to another DNS server (can be a fake/dummy one) for sub.test.dom
2. Create a conditional l forwarder for sub.test.dom

I don't understand though:

 

Q1: How this is possible/makes sense?

Q2: Which one wins/is used when I query for sub.test.dom

Q3: Which one wins/is used when I query for host.sub.test.dom