[DNSOP] About DNS over TCP query pipelining
I am working on the different aspects of the query pipeling (for DNS over TCP or any stream / sequenced packet transport). I try a new tool which sends multiple queries to check which authoritative nameserver implementations support out-of-order responses with a funny result! I never got a conclusive answer: - without unexpected things like on the fly signing auth servers are fast enough to send responses back to back - TCP (slow start?) and network (I tried from my home) delays are greater than server processing delays. So is the pipelining and its head-of-line blocking avoidance idea not appicable? No, and the RFC5966bis I-D is right with its (especially recursive): the processing time of a recursive server depends on external servers when the response is not in the cache. With DNSSEC validating it should be easy to find cases with a big variation in delays. To finish there is a well known real world case where a client could send a flow of queries over TCP to a recursive server: the forwarder case. And more, it is not ridiculous to force the use of TCP with a forwarder... This leads to another question: how to keep the TCP connection opened with a minimal cost (i.e., not sending keep alives :-). There is an I-D about this (in another mailing list thread please). Regards francis.dup...@fdupont.fr ___ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
Re: [DNSOP] About DNS over TCP query pipelining
Francis Dupont francis.dup...@fdupont.fr wrote: I try a new tool which sends multiple queries to check which authoritative nameserver implementations support out-of-order responses with a funny result! You can use adns to do this test too, e.g. with the --tcp query option to adnshost. (Caveat: adnshost does not have any built-in backpressure so it isn't great for bulk DNS lookups. I usually hack adnsresfilter for special bulk lookup jobs like comparing performance of TCP-only with UDP-first.) http://www.chiark.greenend.org.uk/~ian/adns/ Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at/ Plymouth, Biscay, Fitzroy: Southwesterly 3 or 4 in south Fitzroy and south Biscay for a time, otherwise southwesterly 5 to 7, increasing gale 8 for a time. Rough or very rough. Rain or showers. Moderate or good, occasionally poor. ___ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
