DNS 11 DSOTYPENI vs 23 BADCOOKIE
Both DNS 11 (DSOTYPENI) and 23 (BADCOOKIE) belong to the DNS Response Codes (RCODEs) category. 11 indicates that dSO-TYPE Not Implemented. The DNS Stateful Operations (DSO) type in the request is not supported by the server. 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.
Description
DSO-TYPE Not Implemented. The DNS Stateful Operations (DSO) type in the request is not supported by the server.
When You See It
Your client attempted a DSO operation (like a keepalive or push subscription) that the server does not recognize or has not implemented.
How to Fix
Verify that both client and server support the same DSO-TYPE. Upgrade the server software or fall back to traditional DNS queries.
Description
Bad or missing server cookie. The DNS COOKIE option in the request is absent, malformed, or does not match the server's expected value.
When You See It
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.
How to Fix
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.
Key Differences
DNS 11: DSO-TYPE Not Implemented. The DNS Stateful Operations (DSO) type in the request is not supported by the server.
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 11 when your client attempted a DSO operation (like a keepalive or push subscription) that the server does not recognize or has not implemented.
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.
When to Use Which
For 11 (DSOTYPENI): Verify that both client and server support the same DSO-TYPE. Upgrade the server software or fall back to traditional DNS queries. 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.