We continue with a detailed study of Microsoft Azure stack as inferred from an introduction of Azure by Microsoft. We discussed Azure stack is a hybrid approach to cloud. Microsoft Azure has developer tools for all platform services targeting web and mobile, Internet of Things, Microservices, and Data + analytics, Identity management, Media streaming, High Performance Compute and Cognitive services. These platform services all utilize core infrastructure of compute, networking, storage and security. The Azure resource manager has multiple resources, role based access control, custom tagging and self-service templates.
1)  The compute services are made more agile with the offerings from a VM infrastructure, VM scale sets infrastructure, Container service orchestration and batch/Job orchestration. 
2) The Paas platform of Azure can span Azure and AWS both. It can occupy on-Premise, GCP and others as well Containers, serverless and Microservices are different forms of computing. 
3) Azure provides a data platform. The Paas platform of Azure can span Azure and AWS both. It can occupy on-Premise, GCP and others as well Containers, serverless and Microservices are different forms of computing. The consumers for this data transformation to actions are people as well as apps and automated systems.
4) Azure Networking is divided into regions that include inside the Azure region, connecting Azure regions, and geographic reach and internet ecosystems. The networking inside the Azure region already comes with security, performance, load balancing, virtual networks, cross-premises connectivity. Azure comes with accelerated networking
We review some more features of Azure networking. Azure DNS is a globally distributed architecture which is resilient to multiple region failure. The global DNS name resolution is pretty fast with very high availability. It is integrated with the Azure Resource Manager for role based access control, tagging and template based deployment - for both zones and record sets. Azure DNS comes with REST API and SDKs for application integration.
Azure virtual machines support native dual stacks : (IPV4+IPV6) on both flavors of the operating system. It is available globally. It maximizes the reach of Azure applications using mobile (4G) and IoT devices
IPv6 is required by governments and their suppliers. IPV6 has AAAA record.
Azure load balancer services come at different levels. There is the traffic manager for cross region direction and availability and exposure to the internet.  There is the Azure Load Balancer which provides in-region scalability and availability. There is the Azure application gateway which has URL/content based routing and load balancing. Then there is load balancing on the VMs for web servers.
Load Balancers in Azure use multiple VIPs to simplify designs and reduce cost. There are multiple private VIPs on a load balancer and the backend ports are reused using direct server return (DSR) which comes in very useful when there is concern that the load balancer will become a bottleneck. In such cases, the servers are allowed to respond to the client directly such as when the requests are small but the responses are large.

#codingexercise
Find the closest element to a given value in a binary search tree

void GetMinDiff(Node root, int k, ref int diff, ref int key)
{
if (root == null) return;
if (root.data == k){
key == k;
return;
}
if (diff > Math.abs(root.data-k))
{
   diff = Math.abs(root.data -k);
   key = k;
}
if (k <root.data)
     diff = GetMinDiff(root.left, k, ref diff, ref key);
else
     diff = GetMinDiff(root.right, k, ref diff, ref key);
}
The same works for the furthest element from a given value in the same binary search tree with a modification to the comparision of the diff.
In this case, we are trying to maxinize the difference.