[Pdns-dev] What will pdns do when a fast dns server become slow and become fast again?

[jacky]

thank you, Aki, I will use pdns-recursor to implement a feature in my company, so I have to be familiar with the source code to master it.

--  
jacky


On Friday, December 27, 2013 at 3:50 PM, Aki Tuomi wrote:

> 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 (http://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.  
> > >  
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> > > >  
> > > >  
> > >  
> > >  
> > >  
> > >  
> > >  
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