DNS 2 SERVFAIL vs 23 BADCOOKIE
Both DNS 2 (SERVFAIL) and 23 (BADCOOKIE) belong to the DNS Response Codes (RCODEs) category. 2 indicates that server failure. The name server encountered an internal error while processing the query. 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.
Beschreibung
Server failure. The name server encountered an internal error while processing the query.
Wann Sie es sehen
The recursive resolver could not get an authoritative answer — commonly caused by DNSSEC validation failures, unreachable upstream nameservers, or misconfigured zones.
Wie man es behebt
Try a different resolver (e.g., 8.8.8.8 or 1.1.1.1) to isolate the issue. If you control the zone, check DNSSEC signatures, SOA serial consistency, and nameserver reachability.
Beschreibung
Bad or missing server cookie. The DNS COOKIE option in the request is absent, malformed, or does not match the server's expected value.
Wann Sie es sehen
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.
Wie man es behebt
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.
Wesentliche Unterschiede
DNS 2: Server failure. The name server encountered an internal error while processing the query.
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 2 when the recursive resolver could not get an authoritative answer — commonly caused by DNSSEC validation failures, unreachable upstream nameservers, or misconfigured zones.
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.
Wann welchen verwenden
For 2 (SERVFAIL): Try a different resolver (e.g., 8.8.8.8 or 1.1.1.1) to isolate the issue. If you control the zone, check DNSSEC signatures, SOA serial consistency, and nameserver reachability. 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.