Keep OPT out of the record cache
05OPT describes one DNS message and is not cacheable resource data.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 6.2.1 ↗
RFC 6891 · § 6.2.1EXAMPLE
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If EDNS is required, stop rather than silently downgrade.
If EDNS is required, stop rather than silently downgrade.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
RFC 2671RFC 6891 Appendix A
This revision makes OPT support mandatory for compliant implementations and discourages extended label types as a general solution.
Read the updated RFC section ↗The OPT record must not be cached.
- The OPT record must not be cached.
- Fallback without EDNS may be possible, but not if required functionality such as DNSSEC would be lost.
The drawing is a simplified worked example. Follow the linked RFC and its updates for implementation requirements.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
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