resolve: add warning comment to config file

There are way too many users configuring the DNS= setting by mistake,
because what it seems to do is different from what it actually does. We
do not have consensus to change its behavior, so let's at least add a
warning comment.

Fixes #33973

diff --git a/src/resolve/resolved.conf.in b/src/resolve/resolved.conf.in
index 47c9d84c001bddacc92c3edd7c0e1010904eefff..656bc7c0eb7eaa403dd47e4a46695d661f9a68b8 100644 (file)
--- a/src/resolve/resolved.conf.in
+++ b/src/resolve/resolved.conf.in
@@ -21,6 +21,12 @@
 # Cloudflare: 1.1.1.1#cloudflare-dns.com 1.0.0.1#cloudflare-dns.com 2606:4700:4700::1111#cloudflare-dns.com 2606:4700:4700::1001#cloudflare-dns.com
 # Google:     8.8.8.8#dns.google 8.8.4.4#dns.google 2001:4860:4860::8888#dns.google 2001:4860:4860::8844#dns.google
 # Quad9:      9.9.9.9#dns.quad9.net 149.112.112.112#dns.quad9.net 2620:fe::fe#dns.quad9.net 2620:fe::9#dns.quad9.net
+#
+# Using DNS= configures global DNS servers and does not suppress link-specific
+# configuration. Parallel requests will be sent to per-link DNS servers
+# configured automatically by systemd-networkd.service(8), NetworkManager(8), or
+# similar management services, or configured manually via resolvectl(1). See
+# resolved.conf(5) and systemd-resolved(8) for more details.
 #DNS=
 #FallbackDNS={{DNS_SERVERS}}
 #Domains=