From 3c9ee6c04bb0b93f529eabff0ff60f26670770d8 Mon Sep 17 00:00:00 2001
From: Peter Easton <Peter@JollyRogers.ca>
Date: Mon, 24 Feb 2020 05:54:44 +0000
Subject: [PATCH] Add Q&A about private DNS graying out on IP address.

---
 static/faq.html | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/static/faq.html b/static/faq.html
index 03edbc48..e51a7122 100644
--- a/static/faq.html
+++ b/static/faq.html
@@ -68,6 +68,13 @@
                         tracking and silent SMS?</a></li>
                     </ul>
                 </li>
+                <li>
+                    <a href="#day-to-day-use">Day to day use</a>
+                    <ul>
+                        <li><a href="#private-dns">When I enter an IP address into private DNS,
+                        the save button grays out. Why?</a></li>
+                    </ul>
+                </li>
             </ul>
 
             <h2 id="device-support">
@@ -361,6 +368,28 @@
             sending texts or other data is not required or particularly useful to track devices
             connected to a network for an adversary with the appropriate access.</p>
 
+            <h2 id="day-to-day-use">
+                <a href="#day-to-day-use">Day to day use</a>
+            </h2>
+
+            <h3 id="private-dns">
+                <a href="#private-dns">When I enter an IP address into private DNS, the save button
+                grays out. Why?</a>
+            </h3>
+
+            <p>This is not a bug, but rather the feature is operating as it is intended to. When
+            operating in forced mode, private DNS requires a <em>domain</em> and will reject invalid
+            certificates to ensure that the source  is authenticated, not just encrypted. Automatic
+            mode only uses encryption opportunistically, and must be able to fall back to
+            unauthenticated encryption or fall back to plaintext if the DNS server does not support
+            DNS over TLS or the certificate is not valid. Although this does not protect against an
+            active adversary that blocks encrypted communications to the DNS server or will replace
+            the certificates entirely to intercept the encrypted traffic, automatic will
+            transparently provide some opportunistic protection against a passive adversary. When a
+            private DNS provider hostname is specified, the phone will not proceed unless the
+            certificates for TLS are valid and will not fall back to an unauthenticated or plaintext
+            connection should the validation fail.</p>
+
         </div>
         <footer>
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