security best practices update

Author: KingdomOfEnds

articles/digital-twins/security-best-practices.md

@@ -7,7 +7,7 @@ manager: bertvanhoof
 ms.service: digital-twins
 services: digital-twins
 ms.topic: conceptual
-ms.date: 09/30/2019
+ms.date: 11/19/2019
 ---
 
 # Azure Digital Twins security best practices
@@ -33,8 +33,8 @@ Some key practices to safely secure your IoT devices include:
 > * Limit the role of each device, sensor, and person within your IoT space. If compromised, the effect is minimized.
 > * Consider the potential use of device IP address filtering and port restriction.
 > * Limit I/O and device bandwidth to improve performance. Rate-limiting can improve security by preventing denial-of-service attacks.
-> * Keep device firmware up to date.
-> * Periodically audit and review device, network, and gateway security best practices as they continue to improve and evolve.
+> * Keep device firmware, operating system, and software up to date.
+> * Periodically audit and review device, software, network, and gateway security best practices as they continue to improve and evolve.
 
 Some key practices to safely secure an IoT space include:
 
@@ -43,16 +43,19 @@ Some key practices to safely secure an IoT space include:
 > * Require passwords or keys to be periodically changed or refreshed.
 > * Carefully restrict access and permissions by role. See the section [Role-based access control best practices](#role-based-access-control-best-practices) below.
 > * Consider a divided network topology so that devices on each network are isolated from the others.
-> * Use powerful encryption. Require long passwords, and use secure protocols and two-factor authentication.
+> * Use powerful encryption. Require long passwords, use secure protocols, and [multi-factor authentication](https://docs.microsoft.com/azure/active-directory/authentication/concept-mfa-howitworks).
 
 [Monitor](./how-to-configure-monitoring.md) IoT resources to watch for outliers, threats, or resource parameters that fall outside the range of usual operation. Use Azure Analytics for monitoring management.
 
+> [!IMPORTANT]
+> Read Azure [IoT security best practices](../iot-fundamentals/iot-security-best-practices.md) to begin a comprehensive IoT security strategy.
+
 > [!NOTE]
 > For more information on event processing and monitoring, see [Route events and messages with Azure Digital Twins](./concepts-events-routing.md).
 
 ## Azure Active Directory best practices
 
-Azure Digital Twins uses Azure Active Directory to authenticate users and protect applications. Azure Active Directory supports authentication for a variety of modern architectures. They're all based on industry-standard protocols such as OAuth 2.0 or OpenID Connect. A few key practices to secure your IoT space for Azure Active Directory include:
+Azure Digital Twins uses [Azure Active Directory](https://docs.microsoft.com/azure/active-directory/authentication/) to authenticate users and protect applications. Azure Active Directory supports authentication for a variety of modern architectures. They're all based on industry-standard protocols such as OAuth 2.0 or OpenID Connect. A few key practices to secure your IoT space for Azure Active Directory include:
 
 > [!div class="checklist"]
 > * Store Azure Active Directory app secrets and keys in a secure location, such as [Azure Key Vault](https://azure.microsoft.com/services/key-vault/).