Added port and protocol info for Qualys' back-end

Author: memildin

articles/security-center/built-in-vulnerability-assessment.md

@@ -91,7 +91,7 @@ To deploy the vulnerability scanner extension:
 
     Scanning begins automatically as soon as the extension is successfully deployed. Scans will then run at four-hour intervals. This interval is hard-coded and not configurable. 
 
-1. If the deployment fails on one or more VMs, ensure the target VMs can communicate with Qualys's cloud service on the following two IP addresses:
+1. If the deployment fails on one or more VMs, ensure the target VMs can communicate with Qualys's cloud service on the following two IP addresses (via port 443 - the default for HTTPS):
 
     - 64.39.104.113
     - 154.59.121.74 
@@ -150,7 +150,7 @@ You'll need write permissions for any VM on which you want to deploy the extensi
 
 The Azure Security Center Vulnerability Assessment extension (powered by Qualys), like other extensions, runs on top of the Azure Virtual Machine agent. So it runs as Local Host on Windows, and Root on Linux.
 
-During setup, Security Center checks to ensure that the VM can communicate with Qualys's cloud service on the following two IP addresses:
+During setup, Security Center checks to ensure that the VM can communicate with Qualys's cloud service on the following two IP addresses (via port 443 - the default for HTTPS):
 
 - 64.39.104.113
 - 154.59.121.74