diff --git a/sites/default/default.settings.php b/sites/default/default.settings.php
index e3d3c77..9a9591c 100644
--- a/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -193,6 +193,35 @@
  * );
  * @endcode
  *
+ * Any features supported by the PDO driver can be put into
+ * the 'pdo' attribute array, as defined in the php documentation.
+ * @url http://php.net/manual/en/pdo.drivers.php
+ *
+ * Advanced users can also specify MySQL database layer connection security
+ * using the 'pdo' attribute for array as follows:
+ * @code
+ * 'pdo' => [
+ *   MYSQL_ATTR_SSL_KEY => '/path/to/ssl-cert.key',
+ *   MYSQL_ATTR_SSL_CERT => '/path/to/ssl-cert.crt',
+ *   MYSQL_ATTR_SSL_CA => '/path/to/ca-cert.crt',
+ *   // Optional
+ *   MYSQL_ATTR_SSL_CAPATH => '/ca/path',
+ *   MYSQL_ATTR_SSL_CIPHER => 'ssl cipher',
+ * ],
+ * @endcode
+ *
+ * For requiring an SSL connection to a PostgreSQL database add:
+ * @code
+ * $databases['default']['default'] = array(
+ *   'init_commands' => array(
+ *     'sslmode' => 'require',
+ *   ),
+ * );
+ * @endcode
+ *
+ * SQLite databases do not support SSL connection, because they only
+ * live on the localhost.
+ *
  * WARNING: The above defaults are designed for database portability. Changing
  * them may cause unexpected behavior, including potential data loss. See
  * https://www.drupal.org/developing/api/database/configuration for more