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Re: Periodic DNS issues

From: Daniel Stenberg <>
Date: Mon, 12 Mar 2018 23:34:33 +0100 (CET)

On Mon, 12 Mar 2018, Bill Schoolfield wrote:

> We are long time users of libcurl in our C based application. Periodically
> we get "Couldn't resolve host" errors. (Code 6). As best as I can tell there
> seems to be no pattern and the error is very intermittent. It typically
> clears itself within several minutes. We haven't been able to track this
> down. Our suspicion is libcurl is somehow more sensitive to DNS related
> problems but that of course is just a guess.

First, you're using a very very old curl version so while I don't recognize
this as a bug from the past, it isn't completely unthinkable that we've fixed
some bug since then that improved things.

In the configuration your curl is built to use, it calls the stock libc name
resolver functions so it resolves host names exactly like any other typical
program does. It's neither more sensitive nor less sensitive than other

What _can_ make a difference in comparison to other tools you try with
however, is the life-time of your application. A known problem without a
satisfying solution to yet, is the "updated DNS server while running" problem,
as documented in the TODO here:

Received on 2018-03-12