Requirement 1:

Load based fair scheduling

Some domains are requested frequently and others
that are not.
• load on DNS servers should be balanced
• Monitor load on DNS servers and support schedule requests based on current load for improved performance and load balancing

Need:
Option 1: Load-aware scheduling if load on DNS server exceeds the threshold

Option 2: Remove DNS server from scheduling list if the current load is above the specified threshold

Requirement 2:

Avoid co-location of parent and child zone to limit the blast radius for any security attack and for greater high avaialability. 

Co-locating of child zones and parent zone are classic problem of
hosting the DNS server
• Basic DNS configuration, child zone(e.g. foo.example.com) is
delegated from parent zone(e.g. example.ecom) with NS record
• However, in case of new zone(e.g. new-zone.example.com) is
scheduled on pool 0, pool 0’s DNS server(e.g. ns0.example.com) is
return the new zone records without NS record’s delegation on parent
zone.
• There are some DNS problems such as zone hijacking
• Need:
• Avoiding co-locating of child zones and parent zone

https://drive.google.com/file/d/1tKeBS_LEEwK854XN8B-GNzHXmZGSamaa/view?usp=sharing