Hi Matthew, Aha so the files of reference are asr.c ( http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/asr/asr.c?rev=1.31;content-type=text%2Fplain ) and res_send_async.c ( http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/asr/res_send_async.c?rev=1.19;content-type=text%2Fplain )
Do I understand it right that when the DNS resolver fails with a resolve, it actually retries with the *next* DNS server of resolv.conf, and thus for a resolve to fail, 4 DNS servers in a row must be unresponsive within the timeout which is 5 seconds per attempt (ac_nstimeout)? (this is implemented in iter_ns at the bottom of res_send_async.c.) So then, the resolve failures I experienced cannot have been due to failure about an individual DNS server being down, but instead, that it took 4 of them in a row each more than 5 seconds to complete the resolve - and that in turn must have been because of some extremely serious lag about the resolved domain's DNS server? I guess to safeguard for such problems, it would help to have only one DNS server, this being 127.0.0.1, run a local named/dnsmasq/etc., so then that one would get all the four retries, thus relatively increasing the chance by 4x that the resolve will actually look, as the server does caching between resolves so if the first resolve took 17 seconds then the fourth one will be the succeeding one? Thanks, Mikael 2013/12/20 Matthew Dempsky <matt...@dempsky.org> > On Thu, Dec 19, 2013 at 2:36 PM, Mikael <mikael.tr...@gmail.com> wrote: > > a) OpenBSD's resolver configured to retry 999 times before failing, and > > [...] > > If so, is there any way to do a)? > > In src/lib/libc/asr/asr.c, change "ac->ac_nsretries = 4;" to > "ac->ac_nsretries = 999;", recompile, and reinstall. > > However, I wouldn't recommend you actually do this. You should > instead focus on figuring out why your DNS queries are failing in the > first place, and/or fix your downstream users to handle HTTP errors > correctly.
