{"draft":"draft-ietf-dnsop-caching-resolution-failures-08","doc_id":"RFC9520","title":"Negative Caching of DNS Resolution Failures","authors":["D. Wessels","W. Carroll","M. Thomas"],"format":["HTML","TEXT","PDF","XML"],"page_count":"14","pub_status":"PROPOSED STANDARD","status":"PROPOSED STANDARD","source":"Domain Name System Operations","abstract":"In the DNS, resolvers employ caching to reduce both latency for end\r\nusers and load on authoritative name servers.  The process of\r\nresolution may result in one of three types of responses: (1) a\r\nresponse containing the requested data, (2) a response indicating the\r\nrequested data does not exist, or (3) a non-response due to a\r\nresolution failure in which the resolver does not receive any useful\r\ninformation regarding the data's existence.  This document concerns\r\nitself only with the third type.\r\n\r\nRFC 2308 specifies requirements for DNS negative caching.  There,\r\ncaching of TYPE 2 responses is mandatory and caching of TYPE 3\r\nresponses is optional.  This document updates RFC 2308 to require\r\nnegative caching for DNS resolution failures.\r\n\r\nRFC 4035 allows DNSSEC validation failure caching. This document\r\nupdates RFC 4035 to require caching for DNSSEC validation failures.\r\n\r\nRFC 4697 prohibits aggressive requerying for NS records at a failed\r\nzone's parent zone. This document updates RFC 4697 to expand this\r\nrequirement to all query types and to all ancestor zones.","pub_date":"December 2023","keywords":["DNS","Negative","Caching"],"obsoletes":[],"obsoleted_by":[],"updates":["RFC2308","RFC4035","RFC4697"],"updated_by":[],"see_also":[],"doi":"10.17487\/RFC9520","errata_url":"https:\/\/www.rfc-editor.org\/errata\/rfc9520"}