DNS 4 NOTIMP vs 23 BADCOOKIE
Both DNS 4 (NOTIMP) and 23 (BADCOOKIE) belong to the DNS Response Codes (RCODEs) category. 4 indicates that not Implemented. The name server does not support the requested query type or operation. Meanwhile, 23 means that bad or missing server cookie. The DNS COOKIE option in the request is absent, malformed, or does not match the server's expected value.
Descripción
Not Implemented. The name server does not support the requested query type or operation.
Cuándo lo verás
You sent a query type (e.g., IXFR, dynamic update) that the server does not support or has disabled.
Cómo solucionarlo
Verify the server supports the query type you are using. If you need zone transfers or dynamic updates, enable them in the server configuration.
Descripción
Bad or missing server cookie. The DNS COOKIE option in the request is absent, malformed, or does not match the server's expected value.
Cuándo lo verás
Your resolver sent a query without a valid server cookie, or the cookie has expired. This is part of the DNS COOKIE mechanism to prevent spoofed-source attacks.
Cómo solucionarlo
Retry the query — most resolvers automatically learn the correct server cookie from the first response. If the error persists, ensure your resolver supports RFC 7873 DNS Cookies.
Diferencias clave
DNS 4: Not Implemented. The name server does not support the requested query type or operation.
DNS 23: Bad or missing server cookie. The DNS COOKIE option in the request is absent, malformed, or does not match the server's expected value.
You encounter 4 when you sent a query type (e.g., IXFR, dynamic update) that the server does not support or has disabled.
You encounter 23 when your resolver sent a query without a valid server cookie, or the cookie has expired. This is part of the DNS COOKIE mechanism to prevent spoofed-source attacks.
Cuándo usar cada uno
For 4 (NOTIMP): Verify the server supports the query type you are using. If you need zone transfers or dynamic updates, enable them in the server configuration. For 23 (BADCOOKIE): Retry the query — most resolvers automatically learn the correct server cookie from the first response. If the error persists, ensure your resolver supports RFC 7873 DNS Cookies.