RCODE,Name,Description,Reference
0,NoError,No Error,[RFC1035]
1,FormErr,Format Error,[RFC1035]
2,ServFail,Server Failure,[RFC1035]
3,NXDomain,Non-Existent Domain,[RFC1035]
4,NotImp,Not Implemented,[RFC1035]
5,Refused,Query Refused,[RFC1035]
6,YXDomain,Name Exists when it should not,[RFC2136][RFC6672]
7,YXRRSet,RR Set Exists when it should not,[RFC2136]
8,NXRRSet,RR Set that should exist does not,[RFC2136]
9,NotAuth,Server Not Authoritative for zone,[RFC2136]
9,NotAuth,Not Authorized,[RFC8945]
10,NotZone,Name not contained in zone,[RFC2136]
11,DSOTYPENI,DSO-TYPE Not Implemented,[RFC8490]
12-15,Unassigned,,
16,BADVERS,Bad OPT Version,[RFC6891]
16,BADSIG,TSIG Signature Failure,[RFC8945]
17,BADKEY,Key not recognized,[RFC8945]
18,BADTIME,Signature out of time window,[RFC8945]
19,BADMODE,Bad TKEY Mode,[RFC2930]
20,BADNAME,Duplicate key name,[RFC2930]
21,BADALG,Algorithm not supported,[RFC2930]
22,BADTRUNC,Bad Truncation,[RFC8945]
23,BADCOOKIE,Bad/missing Server Cookie,[RFC7873]
24-3840,Unassigned,,
3841-4095,Reserved for Private Use,,[RFC6895]
4096-65534,Unassigned,,
65535,"Reserved, can be allocated by Standards Action",,[RFC6895]