[Gllug] /etc/hosts caching

[Ian Northeast]

Doug Winter wrote:
> On Wed 02 Jun Martin A. Brooks wrote:
> 
>>Microsoft implementations notwithstanding, negative caching is a Good
>>Thing[tm], of course.
> 
> 
> Only when done properly, which is more difficult than it looks.
> 
> "your nameserver didn't respond in time therefore i'm going to pretend
> google doesn't exist until i've been rebooted" is not useful :)

Indeed. But doing it properly isn't that hard surely? On receipt of an 
NXDOMAIN, cache that for the length of its TTL (the domain negative 
caching TTL, often set quite low in non TLDs). On receipt of no answer 
at all or a SERVFAIL, don't cache.

Caching any DNS response and ignoring the TTL is horribly broken. 
Windows isn't the only culprit here, I've seen web browsers including 
Nutscrape running on Linux do it.

Regards, Ian


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