[dns-operations] a note on fetching the root zone using "dig"

Mark Andrews marka at isc.org
Thu Nov 1 22:44:52 UTC 2018

> On 2 Nov 2018, at 9:11 am, Patrick Mevzek <mevzek at uniregistry.com> wrote:
> On 2018-11-01 17:05 -0500, Mark Andrews wrote:> If we don’t change defaults, dig would not be doing EDNS, nor DNS COOKIE both of which are really needed.
> None of these change the output content (like displaying a name as xn-- vs displaying it as pure unicode characters), they just add information respecting the existing format.
> So this would not break existing scripts, and does not create surprise.

But they do hit mis-implementations of the DNS protocol.  Their introduction would have broken some scripts especially if the target server was only STD13 aware.  FORMERR vs NOERROR is a big change.

> And they also do not depend on the environment, while displaying native unicode stuff obviously depend on the locale settings, so things not controlled by the application.

So you can introduce some changes to defaults but not others?

>> +noidnout works with dig compiled w/o idn support.  You get a message to say that it is not supported buy it isn’t fatal.
> There is no such option in my dig 9.9 so when building a script using it, even by putting all flags to make sure to force the results in some way, it would never be able to take that into account and be future proof with later versions.

9.9.9 had unconditional apart from environment variables idn output with IDN support compiled in.

+[no]idnout’s introduction didn’t change the defaults, they were already compile time dependent.

"env IDN_DISABLE=1 dig …” was future proof.  Yes, it is kludgy hence +idnout and later +idnin.

"dig -h | grep ‘+\(\[no\]\)*option[= ]” also works well in determining whether a option is available or not at runtime.

> -- 
> Patrick Mevzek
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Mark Andrews, ISC
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PHONE: +61 2 9871 4742              INTERNET: marka at isc.org

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