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Date: Thu, 15 Nov 2012 01:40:05 +1100
Subject: Re: Subprocess puzzle and two questions
From: Chris Angelico <rosuav@gmail.com>
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Xref: csiph.com comp.lang.python:33338

On Thu, Nov 15, 2012 at 1:22 AM, Roy Smith <roy@panix.com> 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...
>
> import socket
> import time
> s = socket.socket()
> t0 = time.time()
> s.connect(('8.8.8.8', 53))
> t1 = time.time()
> print "it took %f seconds to connect" % (t1 - t0)

That assumes that (a) the remote server supports TCP for DNS (since
UDP is by far the more often used, some name servers don't bother
supporting TCP), and (b) that connection time for TCP is comparable to
ping or an actual DNS lookup. But in terms of approximating your
connection times, that's gotta be way better than shelling out to
several other processes.

ChrisA