It is difficult to envision a "non-recursive DNS resolver" in public service. Recursion is the usual and customary way that DNS names are resolved by the leaf servers, because they are not authoritative for much of anything.

The most common configuration for non-recursive DNS servers is with forwarders. The DNS server accepts queries and simply forwards all of them upstream to another resolver, which... makes its own recursive queries.

It is simply not feasible to avoid having recursive resolvers in the chain of lookups. That's how things work with DNS.

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gumby 6 hours ago | parent [-]

We used to just leave that responsibility to the querying host’s own resolver. I don’t fetishize the end-to-end principle (though I come close) so I suppose a recursive resolver service could be a sort of optimization (plenty of ppl look up, say, gmail.google.com so why not cache it).

In any case, if all resolvers these days are recursive why mention it?

I know this is far from the most important question on the topic of this thread!

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toast0 5 hours ago | parent [-]

> We used to just leave that responsibility to the querying host’s own resolver.

When? I didn't get online until the 90s, but resolv.conf delegating recursion to some other node was the way of the world back then. And still is. Some people do run a recursive resolver locally, but it's not so common afaik.

> In any case, if all resolvers these days are recursive why mention it?

Quad9 is named as a recursive resolver in contrast to being an authoritative server. Quad9 and the server I run for my domain are both DNS servers, both provide name resolution, but one is recursive and the other isn't. Used to be, you might run one server for both jobs, but that fell out of fashion for good reasons.

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SoftTalker 3 hours ago | parent | next [-]

You'd have to go back to the 1980s I think, when systems were still using /etc/hosts and if the host you wanted to talk to wasn't listed there you'd have to use its IP address directly.

IIRC there were some trusted lists of "well known" hosts that were passed around between administrators. DNS was invented because that obviously became impractical quickly as the internet grew.

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lokar 5 hours ago | parent | prev [-]

Back then most computing was done in office, lab, university settings. Running recursive resolvers for the local network was part of the standard IT setup.

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4 hours ago | parent | next [-]

[deleted]

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toast0 4 hours ago | parent | prev [-]

While I agree it was common, running a centralized recursive resolver for the local network is not the same as "leave that responsibility to the querying host’s own resolver"

	▲	lokar 4 hours ago \| parent [-]
		Sure, but it goes with a more centralized approach to systems management in general. The attitude was often that all of the computers were one thing.