RFC 8246 · PROPOSED STANDARD · 2017
SUN · 14 JUN 2026
HTTP Immutable Responses
Overview
RFC 8246, “HTTP Immutable Responses”, is a Proposed Standard document published in September 2017 by P. McManus. The canonical text is published by the RFC Editor.
Abstract
The immutable HTTP response Cache-Control extension allows servers to identify resources that will not be updated during their freshness lifetime. This ensures that a client never needs to revalidate a cached fresh resource to be certain it has not been modified.
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
Read this RFC
The canonical text of RFC 8246 is hosted at rfc-editor.org. Available in TXT,HTML.
Other RFCs from 2017
- RFC 8245 Rules for Designing Protocols Using the Generalized Packet/Message Format from RFC 5444
- RFC 8247 Algorithm Implementation Requirements and Usage Guidance for the Internet Key Exchange Protocol Version 2
- RFC 8244 Special-Use Domain Names Problem Statement
- RFC 8248 Security Automation and Continuous Monitoring Requirements
- RFC 8243 Alternatives for Multilevel Transparent Interconnection of Lots of Links
- RFC 8249 Transparent Interconnection of Lots of Links : MTU Negotiation
- RFC 8242 Interface to the Routing System Ephemeral State Requirements
- RFC 8250 IPv6 Performance and Diagnostic Metrics Destination Option