DNS/BIND/refactoringについて、ここに記述してください。

https://www.isc.org/blogs/bind-9-refactoring/

BIND9 is complex

As we have added to the original BIND9 over the years, the code has gotten increasingly complex. 

How complex is BIND9?
  https://en.wikipedia.org/wiki/Cyclomatic_complexity

Refactoring Targets for BIND 9.12