Dns: NOTIMP is 4 and REFUSED is 5, as RFC 1035 says

DNS_RCODE_NOT_IMPLEMENTED was 5 and DNS_RCODE_REFUSED was 6.

RFC 1035 counts them NOTIMP 4 and REFUSED 5. Code 6 is YXDOMAIN, from the dynamic update committee. Somebody skipped a number, like the CIA skips a floor in the elevator.

-#define DNS_RCODE_NOT_IMPLEMENTED 5
-#define DNS_RCODE_REFUSED         6
+#define DNS_RCODE_NOT_IMPLEMENTED 4
+#define DNS_RCODE_REFUSED         5

Impact

None at runtime. Nothing reads these defines yet, and the client does not look at the rcode of an answer at all, so no answer was ever misread. The numbers are fixed before anybody trusts them.

Two defines, no ISO rebuild.