diff --git a/doh-server/doh-server.conf b/doh-server/doh-server.conf
index e6c88c0..8d91195 100644
--- a/doh-server/doh-server.conf
+++ b/doh-server/doh-server.conf
@@ -5,9 +5,14 @@ listen = [
 ]
 
 # TLS certification file
+# If left empty, plain-text HTTP will be used.
+# Please be informed that this program does not do OCSP Stapling, which is
+# necessary for some clients to bootstrap itself.
+# You are recommended to use a server load balancer (Caddy, Nginx) and set up
+# TLS there.
 cert = ""
 
-# TLS key file
+# TLS private key file
 key = ""
 
 # HTTP path for resolve application