Tests todo:

A - SERVFAIL - should return empty response, ra 0
A - NXDOMAIN - should return SOA
A - NOERROR - should return A record
            - or delegated NS record

Record delegated to self should return SOA record rather than NS delegation

Casing should match on question section, always.

Casing should match on other sections if a direct match? (not required, but efficient for compression pointers)
  - www.EXample.COm + example.com = EXample.COm
  - EXample.COm + www.example.com = www.EXample.COm
  - (this should be taken care of by compression pointer logic, once implemented)