clearing local caches
Scott Haneda
talklists at newgeo.com
Wed Jul 15 20:07:19 UTC 2009
On Jul 15, 2009, at 12:59 PM, Dave Sparro wrote:
> Scott Haneda wrote:
>> On Jul 15, 2009, at 12:29 PM, Dave Sparro wrote:
>>> Scott Haneda wrote:
>>>> ... However, I would like to just get DNS response times.
>>>>
>>>> Perhaps take the list of hosts and feed them to a iterative
>>>> script calling dig, and fish out the response time? This does
>>>> add the problem of redirects of course would not be followed, so
>>>> I would have to pre-fetch all my urls and follow them to get my
>>>> testing list.
>>>
>>> I don't see how you could call the results from any other method
>>> "DNS response times."
>>>
>>> If you used a web browser to measure from, you'd be introducing
>>> all sorts of other latencies. Delays from the web server
>>> itself. The webserver may have to talk to a database to output
>>> the HTML. The transfer of the actual HTML code isn't
>>> instantaneous. (ad that's just off the top of my head).
>> Correct. So I will end up pulling down the file, extracting the
>> hostnames, following any redirects, and extracting the resulting
>> hostnames. This gives me a nice list of hostnames that I can run
>> through an iterative loop in dig.
>> I just need to make sure that I am not getting a locally cached
>> result. I suspect there is no way to force a non caches result
>> from the remote ended resolver?
>
> If you aim your dig at a specific DNS server you'll be getting the
> results from that IP address. There won't be any local resolver
> involved.
>
> If you aren't in control of the remote resolver, there's no way to
> predict the cache status of your query on the remote side.
Thank you, makes sense, I will give it a shot.
--
Scott * If you contact me off list replace talklists@ with scott@ *
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