The IESG has approved the following document: - 'Serving Stale Data to Improve DNS Resiliency' (draft-ietf-dnsop-serve-stale-10.txt) as Proposed Standard
This document is the product of the Domain Name System Operations Working Group. The IESG contact persons are Warren Kumari, Ignas Bagdonas and Barry Leiba. A URL of this Internet Draft is: https://datatracker.ietf.org/doc/draft-ietf-dnsop-serve-stale/ Technical Summary This draft defines a method (serve-stale) for recursive resolvers to use stale DNS data to avoid outages when authoritative nameservers cannot be reached to refresh expired data. It updates the definition of TTL from RFCs 1034, 1035, and 2181 to make it clear that data can be kept in the cache beyond the TTL expiry and used for responses when a refreshed answer is not readily available. Working Group Summary This draft dates to March 2017 and was adopted by DNSOP in October 2017. It's been extensively reviewed in the WG. The primary point of controversy was that it discusses an optional protocol change (the choice by a recursive resolver to re-use data beyond the authoritative server TTL when no refresh is available) that some WG participants felt to be unwise under some conditions. The discussion of timer values in Sec. 5, and of implementation decisions and caveats in Sec. 6 and Sec. 7, seem to address these concerns. Since this protocol modification is widely implemented and deployed, having a standards track description seemed to promote careful practice and interoperability. Document Quality The protocol update discussed in this draft is an attempt to document behavior that is implemented in multiple open source DNS codebases and deployed by a number of large operators, including DNS services and CDNs that rely on the specified DNS behavior. Common practice regarding the handling of TTLs by recursive resolvers has changed considerably over the behavior originally specified, and documenting the current practice as an update to the protocol seems likely to promote interoperability and transparency under both normal and adverse conditions. Personnel Suzanne Woolf (shepherd) Barry Leiba (AD) _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop