Re "recursive queries", an interesting thing came up yesterday...
http://www.unbound.net/downloads/CVE-2014-8602.txt > Resolvers fetch the content for domain names by sending queries to > authority servers on the internet. One of the responses that authority > servers can return is a referral response, which points to further > servers to continue the lookup. To continue the lookup, resolvers > may have to perform recursion, where new names, called glue, from the > referral response have to be looked up to continue the query resolution. This is not the usual DNS meaning of recursion. Referrals occur during *iterative* resolution. (Also, tangential to the point of this message, delegation NS records are not glue - if there is glue in the response, it isn't necessary to find the addresses of the NS targets!) I have spent a little time trying to see what these sub-queries are called in other contexts. RFC 1034 section 5.3.3 says: > The top level algorithm has four steps: > > 1. See if the answer is in local information, and if so return > it to the client. > > 2. Find the best servers to ask. > > 3. Send them queries until one returns a response. > > 4. Analyze the response, [...] The question is, what do you call the queries made in step 2? BIND has various functions with "find" in the name which deal with finding name server addresses. I don't think it has a more special name for this part of the iterative process. I can see why Unbound calls them "recursive" queries, from the structure of the process, but it is a really unhelpful choice of word given its other very different meaning in the context of the DNS. There are a few places in the RFCs where these are referred to as "parallel" queries, e.g. later in RFC 1034 section 5.3.3, > The resolver has many choices here; the best is to start parallel > resolver processes looking for the addresses while continuing onward > with the addresses which are available. and RFC 1035 section 7.1 (noted by Peter van Dijk), > Note that if the resolver structure allows one request to > start others in parallel, such as when the need to access a > name server for one request causes a parallel resolve for the > name server's addresses, the spawned request should be started > with a lower counter. This prevents circular references in > the database from starting a chain reaction of resolver > activity. Tony. -- f.anthony.n.finch <d...@dotat.at> http://dotat.at/ Rockall, Malin, Hebrides, Bailey, Fair Isle: South veering west or southwest, gale 8 to storm 10, occasionally violent storm 11 in Rockall and Bailey later. Very rough or high, becoming very high or phenomenal. Rain, then squally wintry showers. Moderate or poor, occasionally good. _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
