Hi, I already said this in private, but will also mention it here: I like this idea.
Some initial comments: 1. Why actually define a new option for this. Since the option only uses one bit to request/acknowledge opportunistic refresh, can't we use one bit from the Z field from the OPT Record TTL Field? 2. The draft says: If Client Subnet [RFC7871] is enabled, resource records in the cache may be associated with a subnet. In these cases, the resolver MUST ensure that the zone serial number associated with such records is obtained from an SOA record associated with the identical subnet. But a SOA record is not associated with a subnet, and most likely will return with a SCOPE of 0 since the option is not actually used to generate the response. Typically with Client Subnet only address records (A, AAAA) will result in a tailored response. Also, an authoritative name server may generate a different response for QTYPE=AAAA while the SOA record has not changed. It would be tricky to make opportunistic refresh work with Client Subnet. It would definitely require more thought, but I would also be fine with just specifying it does not work with ECS. 3. Security Considerations I think this could use some words on the risk that an adversary tries to make a record stick in the cache for longer than it is allowed, by spoofing a response with an additional SOA record (this can be stopped with DNSSEC obviously). Best regards, Matthijs On 03-07-17 13:36, Stephen Morris wrote: > Hi > > We have submitted a new draft which attempts to formalize an idea that > has been kicking around for a couple of years, namely to use serial > number information from DNS responses to determine whether stale records > in a cache can be refreshed without the need for an upstream query. > > Please send comments and feedback to the list. > > Stephen > > > > -------- Forwarded Message -------- > Subject: New Version Notification for > draft-muks-dnsop-dns-opportunistic-refresh-00.txt > Date: Fri, 30 Jun 2017 13:41:45 -0700 > From: internet-dra...@ietf.org > To: Mukund Sivaraman <m...@isc.org>, Shane Kerr > <sh...@timetravellers.org>, Stephen Morris <step...@isc.org> > > > A new version of I-D, draft-muks-dnsop-dns-opportunistic-refresh-00.txt > has been successfully submitted by Mukund Sivaraman and posted to the > IETF repository. > > Name: draft-muks-dnsop-dns-opportunistic-refresh > Revision: 00 > Title: DNS Opportunistic Refresh for Resolvers > Document date: 2017-06-29 > Group: Individual Submission > Pages: 9 > URL: > https://www.ietf.org/internet-drafts/draft-muks-dnsop-dns-opportunistic-refresh-00.txt > Status: > https://datatracker.ietf.org/doc/draft-muks-dnsop-dns-opportunistic-refresh/ > Htmlized: > https://tools.ietf.org/html/draft-muks-dnsop-dns-opportunistic-refresh-00 > Htmlized: > https://datatracker.ietf.org/doc/html/draft-muks-dnsop-dns-opportunistic-refresh-00 > > > Abstract: > This document describes a mechanism whereby a DNS resolver can > opportunistically refresh the TTLs of cached records of a zone using > serial number information carried in responses from the zone's > nameservers. As well as improving resolver response time by reducing > the need to make upstream queries, the mechanism can also reduce the > workload of authoritative servers. > > > > > Please note that it may take a couple of minutes from the time of > submission until the htmlized version and diff are available at > tools.ietf.org. > > The IETF Secretariat > > _______________________________________________ > DNSOP mailing list > DNSOP@ietf.org > https://www.ietf.org/mailman/listinfo/dnsop > _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
