Document some reasonable DNS servers in the example config file

We have an option to set the fallback list, so we don't know what the contents
are. It may in fact be empty. Let's add some examples to make it easy for a user
stranded without any DNS to fill in something that would work. As a bonus, this
also gives names to the entries we provide by default.
(I added google and cloudflare because that's what we have currently, and quad9
because it seems to be a good privacy-concious and fast choice and was requested
in #12499. As a minimum, things we should include should be well-known global
services with a documented privacy policy and both IPv4 and IPv6 support and
decent response times.)

diff --git a/src/resolve/resolved.conf.in b/src/resolve/resolved.conf.in
index 082ad7162610993c8098fcefa01d8c464ec00f07..514021792fc65b0a48a2a726f93df94517547d80 100644 (file)
--- a/src/resolve/resolved.conf.in
+++ b/src/resolve/resolved.conf.in
@@ -12,6 +12,10 @@
 # See resolved.conf(5) for details
 
 [Resolve]
+# Some examples of DNS servers which may be used for DNS= and FallbackDNS=:
+# Cloudflare: 1.1.1.1 1.0.0.1 2606:4700:4700::1111 2606:4700:4700::1001
+# Google:     8.8.8.8 8.8.4.4 2001:4860:4860::8888 2001:4860:4860::8844
+# Quad9:      9.9.9.9 2620:fe::fe
 #DNS=
 #FallbackDNS=@DNS_SERVERS@
 #Domains=