(Another issue raised due to T74674)
http://dk.wikipedia.org redirecting to http://da.wikipedia.org appears to have been an anomaly from 2002 (see http://comments.gmane.org/gmane.science.linguistics.wikipedia.international/712), before the language committee and it was extended in T17357 to http://dk.wikibooks.org and http://dk.wiktionary.org despite the input of the language committee being very negative.
IMO it should be removed, so it can not be used any longer as an interlanguage link in content pages, which means wikitext parsers need to recognise 'dk' as an interwiki langlink prefix and know that it is equivalent to da, but only on three of the Wikimedia projects. Ugh!
Is there any other country code used as a subdomain on multi-lang projects that redirects to the language subdomain of that country?
But if this annoyance must persist, it would be a bit less annoying if it was consistently annoying.
..all redirect to URLs like https://incubator.wikimedia.org/wiki/Wq/dk?goto=mainpage , which says
"dk" Wikivoyage (unknown language code). A Wikiquote in this language does not yet exist.
(another bug: there is html syntax in the title) with slight differences for Wikivoyage of course.
This wiki does not exist. Unfortunately, Wikiversity in "dk" does not exist on its own domain yet, or it has been closed. You may like to visit Beta Wikiversity to start or improve dk Wikiversity there.