Source: https://docs.microsoft.com/en-us/azure/load-balancer/load-ba...
Source: https://docs.microsoft.com/en-us/azure/load-balancer/load-ba...
It seems that once you add a load balancer, all traffic gets funneled through it, doesn't matter if it was addressed to it or not. Which is unlike any other load balancer I have ever seen.
Coming from other clouds, this was a shock.
The only thing comparable is AWS's NLB. Because that load balancer is so transparent, clients appear to be connecting directly, with the original source ip. Which caused issues when I wanted to deploy my own Elasticsearch and use an internal NLB for master discovery (whenever a request got routed to the same machine packets got discarded by the kernel). But you can just switch to another load balancer then.
There is an excellent Network Academy video on YouTube [1] that covers some of the internal implementations of the layer-4 load balancers (in the context of HA for NVA's).