When setting up a load balancing rule in Azure, you’ll be given the opportunity to enable/disable “Direct Server Return”.
So what does it do?
Apart from disabling the “backend port” input field, what does it do? Clicking on the “?” gives us a start…
Basically, DSR (Direct Server Return) will disable any NAT involved. So the targetted VM should be aware of the loadbalancer IP, or the network flow will break.
So it’s usefull to use as a cluster IP address (for example, when using a cluster IP), though do NOT use it for typical load balancing scenario’s where the nodes aren’t aware of the cluster address.