Andrew Sullivan <a...@anvilwalrusden.com> wrote: > > Joe Abley and I have just submitted a draft > (https://datatracker.ietf.org/doc/draft-sullivan-dnsop-refer-down/) > that is intended to capture the discussion here about referrals and > how to describe them. It is intended for BCP, and it discourages > upward referrals by authoritative servers. > > That leaves the task of the referrals definition. I have some new > text below:
Regarding the definition of referrals from older RFCs, see my terminology review from May 2015: https://www.ietf.org/mail-archive/web/dnsop/current/msg14243.html As far as I can tell, RFC 1034 uses the term "referral" for downward referrals. For instance, section 4.2.1: To fix this problem, a zone contains "glue" RRs which are not part of the authoritative data, and are address RRs for the servers. These RRs are only necessary if the name server's name is "below" the cut, and are only used as part of a referral response. Section 4.3.1: A referral to name servers which have zones which are closer ancestors to the name than the server sending the reply. I think that quote implies that other less formal uses of "closer" specifically mean downward in the DNS tree. The downward meaning is most clear in the algorithm in section 4.3.2. Step 3 deals with authoritative data, and says: b. If a match would take us out of the authoritative data, we have a referral. This happens when we encounter a node with NS RRs marking cuts along the bottom of a zone. Step 4 is where upward referrals come from (when the cache only contains root hints and no authoritative zone matches the qname), but it does NOT use the term "referral": 4. Start matching down in the cache. If QNAME is found in the cache, copy all RRs attached to it that match QTYPE into the answer section. If there was no delegation from authoritative data, look for the best one from the cache, and put it in the authority section. Go to step 6. So I think unqualified "referral" means "downward referral" (from authoritative data); it's OK to use the term "upward referral" to mean a response from the cache that looks like a referral but doesn't help to answer the query. I have also seen the term "implicit referral" meaning the authority section from a recursive response, since the idea was that a downstream cache might use those records to answer future queries more efficiently (though doing that is no longer considered safe). Tony. -- f.anthony.n.finch <d...@dotat.at> http://dotat.at/ - I xn--zr8h punycode Fisher: Northerly 3 or 4, increasing 5 or 6, then becoming cyclonic later. Moderate, occasionally rough in west. Showers, wintry later. Good, occasionally poor later. _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
