[Twisted-Python] Custom DNS server
exarkun at intarweb.us
Wed Jul 23 18:48:58 EDT 2003
On Wed, Jul 23, 2003 at 10:50:00PM +0200, Rudy Schockaert wrote:
> Jp Calderone wrote:
> > This should be pretty easy. I think the way to go about it would be to
> >subclass t.names.client.Resolver and override lookupMailExchange(),
> >returning the central relay address instead for the affected domains, and
> >deferring (english meaning) to the parent implementation of the method for
> >everyone else.
> Hi Jp,
> I have two caches: one preloaded with my entries and a second one that
> is empty at the start.
> When a request arrives for a record that is in my preloaded cache it is
> returned, but also added to the second cache (actually to the last cache
> passed to the DNSServerFactory)..
> callLater in cacheResult will remove it later from the second cache but
> not from the first cache.
> All other entries will follow the normal way, be it with one
> cache-lookup extra.
> Is there somewhere an error in my reasoning? Are there other reasons why
> this is not a good approach?
This looks like a pretty good solution, actually. I wish I'd thought of
The only possible problem I can imagine is that the extra latency created
by the extra cache miss before most lookups may confuse some clients -- but
on a modern piece of hardware (something I don't have myself, hence my
concern about such things :), I doubt this would actually be a problem.
"One World, one Web, one Program." - Microsoft(R) promotional ad
"Ein Volk, ein Reich, ein Fuhrer." - Adolf Hitler
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