once cache expires the records are removed and are looked for again. if you look at SyncRes::getAddrs, you'll see the record selection process.
btw, are you just interested or is there some deeper issue here? Aki On Fri, Dec 27, 2013 at 03:29:27PM +0800, jacky wrote: > hi, Aki tnuomi， > Thank you for suggestion. I found pdns always get the fastest one from the > front of result returned by function "SyncRes::shuffleInSpeedOrder”. If a > slow one at the back has no opportunity to be choosed, how pdns know it > become fast. I can not find the source code make pdns query the slow one. > > on the other hand, I found there is a houseKeeping thread which will erase > the stale speed value of a dns server . If a slow dns at the back of > t_sstorage->nsSpeeds map, it will be erased because of rarely to be queried, > and only fast dns server will have its speed updated by this code " > t_sstorage->nsSpeeds[*tns].submit(*remoteIP, lwr.d_usec, &d_now);” at > syncres.cc:1003. > . And then, only dns servers which are mostly queried will stay in > t_sstorage->nsSpeeds map. It make me puzzled. > > -- > jacky > > > On Friday, December 27, 2013 at 3:08 PM, Aki Tuomi wrote: > > > On Thu, Dec 26, 2013 at 10:34:23PM +0800, jacky wrote: > > > hi, all, > > > I think may be it is a question more suitable to dev maillist, so I > > > submit it here. If I made a mistake , please let me know. Thanks. > > > > > > I'am reading the source code of pdns-recursor-3.5.3. There is question I > > > can not understand. > > > When a authoritative dns server become slow because of overload, > > > pdns-recursor will move it backwards in the > > > t_sstorage->nsSpeeds map, and then a faster dns server will be used > > > preferred. But when the dns server recoverd > > > from overload and become fast again, what will pdns-recursor do about it > > > ? Will pdns-recursor move it forward > > > in speed map? I can't find relevant source code. Any suggestion? > > > > > > -- > > > jacky > > > > > > > > > Hi! > > > > It works by moving the fastest one on top. > > > > > _______________________________________________ > > > Pdns-dev mailing list > > > Pdns-dev@mailman.powerdns.com (mailto:Pdns-dev@mailman.powerdns.com) > > > http://mailman.powerdns.com/mailman/listinfo/pdns-dev > > > > > > > > > > >
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