Re: What will pdns do when a fast dns server become slow and become fast again?

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
> > > [email protected] (mailto:[email protected])
> > > http://mailman.powerdns.com/mailman/listinfo/pdns-dev
> > >  
> >  
> >  
> >  
> 
>

_______________________________________________
Pdns-dev mailing list
[email protected]
http://mailman.powerdns.com/mailman/listinfo/pdns-dev

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)

iEYEARECAAYFAlK9MVEACgkQahHbMDrZuj45hACeOjuoLTebQWF/7GHbfhI9gCLG
5cYAoJAZNUH9WSTaSYAj992YaAA2uCJw
=5YnA
-----END PGP SIGNATURE-----