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Groups > comp.lang.python > #33346

Re: Subprocess puzzle and two questions

From roy@panix.com (Roy Smith)
Newsgroups comp.lang.python
Subject Re: Subprocess puzzle and two questions
Date 2012-11-14 11:20 -0500
Organization PANIX -- Public Access Networks Corp.
Message-ID <k80gd6$t0q$1@panix2.panix.com> (permalink)
References <mailman.3664.1352867713.27098.python-list@python.org> <mailman.3666.1352873042.27098.python-list@python.org> <roy-F5C640.09225714112012@news.panix.com> <mailman.3684.1352904008.27098.python-list@python.org>

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I wrote:
>> Oh, my.  You're using DNS as a replacement for ping?  Fair enough.  In
>> that case, all you really care about is that you can connect to port 53
>> on the server...
>>
>> s = socket.socket()
>> s.connect(('8.8.8.8', 53))

In article <mailman.3684.1352904008.27098.python-list@python.org>,
Chris Angelico  <rosuav@gmail.com> wrote:
>That assumes that (a) the remote server supports TCP for DNS

This is true.  I honestly don't know what percentage of DNS servers
out there only support UDP.  The two I tried (Google's 8.8.8.8, and my
Apple TimeCapsule) both supported TCP, but that's hardly a
representitive sample.

> and (b) that connection time for TCP is comparable to
> ping or an actual DNS lookup.

My first thought to solve both of these is that it shouldn't be too
hard to hand-craft a minimal DNS query and send it over UDP.  Then, I
hunted around a bit and found that somebody had already done that, in
spades.  Take a look at http://www.dnspython.org; it might be exactly
what's needed here.

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Thread

Subprocess puzzle and two questions wrw@mac.com - 2012-11-13 22:34 -0500
  Re: Subprocess puzzle and two questions Roy Smith <roy@panix.com> - 2012-11-13 23:41 -0500
    Re: Subprocess puzzle and two questions William Ray Wing <wrw@mac.com> - 2012-11-14 00:03 -0500
      Re: Subprocess puzzle and two questions Roy Smith <roy@panix.com> - 2012-11-14 09:22 -0500
        Re: Subprocess puzzle and two questions Chris Angelico <rosuav@gmail.com> - 2012-11-15 01:40 +1100
          Re: Subprocess puzzle and two questions roy@panix.com (Roy Smith) - 2012-11-14 11:20 -0500
            Re: Subprocess puzzle and two questions Chris Angelico <rosuav@gmail.com> - 2012-11-15 08:54 +1100
              Re: Subprocess puzzle and two questions Roy Smith <roy@panix.com> - 2012-11-14 20:49 -0500
                Re: Subprocess puzzle and two questions Chris Angelico <rosuav@gmail.com> - 2012-11-15 13:04 +1100
                Re: Subprocess puzzle and two questions Roy Smith <roy@panix.com> - 2012-11-14 21:10 -0500
                Re: Subprocess puzzle and two questions Chris Angelico <rosuav@gmail.com> - 2012-11-15 13:21 +1100
                Re: Subprocess puzzle and two questions Dave Angel <d@davea.name> - 2012-11-14 21:55 -0500
                Re: Subprocess puzzle and two questions Kushal Kumaran <kushal.kumaran+python@gmail.com> - 2012-11-15 10:23 +0530
                Re: Subprocess puzzle and two questions Nobody <nobody@nowhere.com> - 2012-11-15 22:54 +0000
                Re: Subprocess puzzle and two questions Roy Smith <roy@panix.com> - 2012-11-15 20:07 -0500
                Re: Subprocess puzzle and two questions Nobody <nobody@nowhere.com> - 2012-11-17 00:17 +0000
              DNS from Python (was Re: Subprocess puzzle and two questions) aahz@pythoncraft.com (Aahz) - 2012-11-14 21:42 -0800
        Re: Subprocess puzzle and two questions wrw@mac.com - 2012-11-14 09:37 -0500
  Re: Subprocess puzzle and two questions Tim Roberts <timr@probo.com> - 2012-11-13 23:17 -0800

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