We continue with a detailed study of Microsoft Azure stack as inferred from an introduction of Azure by Microsoft. We reviewed some more features of Azure networking. 
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 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
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). Secondary NICs associated are also provided to enable connectivity to restricted vnet. Load balancer can now be setup with internal and external VIP with direct public association. Moreover, a NIC can now have multiple private IPs - static or dynamic and multiple public IPs - static or dynamic and unlocks NVA partners.  Application Gateway has layer 7 application delivery controller features. It can enforce security with SSL termination and allow/block SSL protocol versions. It can manage session and site with cookie based session affinity and muti-site hosting. It can manage content with URL based routing. It can manage backend with rich diagnostics including access and performance logs, VM scale set support and custom health probes.
The Web application firewall has also been significantly improved based on Open Web Application Security Project (owasp.org). WAF security protects applications from web based intrusions and is built using ModSecurity and CoreRule set. It is highly available and fully managed. It is preconfigured for most common web vulnerabilities such as SQL injection and XSS attacks.
Cross premises connectivity is maintained with P2S SSTP tunnels and IPSEC S2S VPN tunnels to Azure over Internet. If there is a private WAN, an ExpressRoute is maintained to Azure.
Print the largest BST in a given binary tree
int GetMaxBST(Node root)
{
if (IsBST(root))
    return treesize(root);
return Math.max( GetMaxBST(root.left), GetMaxBST(root.right));
}

bool isBST(node root)
{
return IsBstHelper(root, INT_MIN, INT_MAX);
}

bool IsBstHelper(node root, int min, int max)
{
 if (root==null) return true;
 if (root.data < min || root.data> max) return false;
return IsBstHelper(root.left, min, root.data-1) &&
           IsBstHelper(root.right, root.data+1, max);

}
int treesize(Node root)
{
if (root == null) return 0;
return treesize(root.left) + treesize(root.right) + 1;
}

we could also combine the operations above to make the traversals more efficient.
int GetMaxBST(node root, int min, int max)
{
if (root == null) return 0;
if (root.data < min || root.data > max) return 0;
int left = GetMaxBST(root.left, min, root.data - 1);
int right = GetMaxBST(root.right, root.data+1, max); 
if (left >= 0 && right >= 0)
    return  left + right + 1;
return 1; 
}