diff --git a/doc/arm/Bv9ARM.ch06.html b/doc/arm/Bv9ARM.ch06.html
index dd8d8ca33f..d59d9d198b 100644
--- a/doc/arm/Bv9ARM.ch06.html
+++ b/doc/arm/Bv9ARM.ch06.html
@@ -14,7 +14,7 @@
- OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
- PERFORMANCE OF THIS SOFTWARE.
-->
-
+
@@ -1892,7 +1892,15 @@ IPv6, there is a separate query-source-v6
If address is * (asterisk) or is omitted,
a wildcard IP address (INADDR_ANY) will be used.
If port is * or is omitted,
-a random unprivileged port will be used. The avoid-v4-udp-ports
+a random unprivileged port number is picked up and will be
+used for each query.
+It is generally strongly discouraged to
+specify a particular port for the
+query-source or
+query-source-v6 options;
+it implicitly disables the use of randomized port numbers
+and leads to insecure operation.
+The avoid-v4-udp-ports
and avoid-v6-udp-ports options can be used to prevent named
from selecting certain ports. The defaults are:
query-source address * port *;