[blfs-dev] Today's new packages

Rob Landley rob at landley.net
Thu Aug 15 14:53:43 PDT 2013


On 08/14/2013 01:57:33 PM, Bruce Dubbs wrote:
> Armin K. wrote:
> > On 08/14/2013 08:02 PM, Bruce Dubbs wrote:
> >> Armin K. wrote:
> >>>
> >>> ffmpeg 1.2.2
> >>
> >> Just went out to look and http://ffmpeg.org/ gives me unknown  
> host.  Do
> >> you have a different site?
> >
> > Works here. http://ffmpeg.org/releases/
> >
> > Although it's a bit slow (I do use bind9 on my laptop and it is not
> > caching dns server).
> 
> Must have been a transient issue because it works for me now,  
> although,
> as you say, it's slow.

If the public DNS server you're querying hasn't got the authoritative  
answer to a domain lookup cached, it may have to go through a longish  
chain of zone delegations to find it, each with its timeout/retransmit  
and cacheing period. With loaded servers your query can time out before  
it's done, and even if the DNS server is still following the delegation  
chain. And even if the DNS server you delegated the query to gives up  
halfway through, it probably smaded it through part of the chain and  
cached the zone delegations it _did_ manage to look up, so your later  
query can start halfway through the process and has a better chance of  
succeeding. (At least for the rest of the cache period timeout.)

This kind of failure-then-success basically means that nobody else  
using your DNS server has looked up that domain in longer than the  
timeout period (for ffmpeg 86400 seconds is 24 hours), so it dropped  
out of the cache. One reason to use <strike>the NSA's</strike> Google's  
public DNS servers (8.8.8.8 and 8.8.4.4) is they tend to have  
everything cached.

Rob


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