Constants
BADALG = 21
BADNAME = 20
BADMODE = 19
BADTIME = 18
BADKEY = 17
BADSIG = 16
BADVERS = 16
NotZone = 10
NotAuth = 9
NXRRSet = 8
YXRRSet = 7
YXDomain = 6
Refused = 5
NotImp = 4
NXDomain = 3
ServFail = 2
FormErr = 1
NoError = 0