Well, there is https://www.freedesktop.org/software/systemd/man/systemd-res... but you may or may not think that's part of the "OS".

That's misleading. The way that this has worked for decades on Linux-based operating systems and on Unices is that one installs a local caching DNS proxy, choosing one of the many available: ISC's BIND, Bernstein's dnscache, unbound, dnsmasq, PowerDNS, MaraDNS, and so forth.

Every Unix system having a local caching DNS proxy was and is as much a norm as every Unix system having a local MTS. A quarter of a century ago, this would have been BIND and Sendmail. Things are more variable, now.

To illustrate that this was considered the norm, here is a random book from the 1990s. Smoot Carl-Mitchell's _Practical Internetworking with TCP/IP and UNIX_ says, quite unequivocally:

> You must run a DNS server if you have Internet connectivity. The most common UNIX DNS server is the Berkeley Internet Name Daemon (BIND), which is part of most UNIX systems.

People sometimes think that this is not the case nowadays, and the fact that a computer is a personal computer magically means that a Unix or Linux-based operating system should offload this task and not perform it locally. They are wrong, and that is DOS Think. Ironically, they don't even get to play the resource allocation card nowadays. The amount of memory and network bandwidth that needs to be devoted to caching proxy DNS service on a personal computer is dwarfed by the amounts nowadays consumed by WWW browsers and HTTP(S).

There's no similar argument for a node in a datacentre.

Ideally, not only should every machine have a (forwarding/resolving) caching proxy DNS server, every organization (or LAN, or even machine) should have a local root content DNS server. A lot of (quite valid) DNS lookups stop at the root with fixed or negative answers. Stopping that from leaving the site/LAN/machine is beneficial.

Ironically, putting a forwarding caching proxy DNS service on the local end of any congested, slow, expensive, or otherwise limited link is advice that I and others have been handing out for over 20 years. It's exactly what one should be doing with things like Amazon's non-local proxy DNS server limited to 1024 packets/second/interface.

* http://jdebp.uk./FGA/dns-server-roles.html#ChoosingProxy

So the question is not whether there a local DNS cache mechanism exists. It's whether it's set up by the company dishing out the VMs, and if not why not. Amazon provides instructions on how to add dnsmasq, and clearly labels this as how to reduce DNS outages. So it's not even the case that Amazon is wrongly discouraging having local caching proxy DNS servers.

* https://aws.amazon.com/premiumsupport/knowledge-center/dns-r...