- Unlike public Load Balancers which provide [outbound connections](load-balancer-outbound-connections.md) when transitioning from private IP addresses inside the virtual network to public IP addresses, internal Load Balancers do not translate outbound originated connections to the front-end of an internal Load Balancer as both are in private IP address space. This avoids potential for SNAT exhaustion inside unique internal IP address space where translation is not required. The side effect is that if an outbound flow from a VM in the back-end pool attempts a flow to front-end of the internal Load Balancer in which pool it resides _and_ is mapped back to itself, both legs of the flow don't match and the flow will fail. If the flow did not map back to the same VM in the back-end pool which created the flow to the front-end, the flow will succeed. When the flow maps back to itself the outbound flow appears to originate from the VM to the front-end and the corresponding inbound flow appears to originate from the VM to itself. From the guest OS's point of view, the inbound and outbound parts of the same flow don't match inside the virtual machine. The TCP stack will not recognize these halves of the same flow as being part of the same flow as the source and destination don't match. When the flow maps to any other VM in the back-end pool, the halves of the flow will match and the VM can successfully respond to the flow. The symptom for this scenario is intermittent connection timeouts. There are several common workarounds for reliably achieving this scenario (originating flows from a back-end pool to the back-end pools respective internal Load Balancer front-end) which include either insertion of a third-party proxy behind the internal Load Balancer or [using DSR style rules](load-balancer-multivip-overview.md). While you could use a public Load Balancer to mitigate, the resulting scenario is prone to [SNAT exhaustion](load-balancer-outbound-connections.md#snat) and should be avoided unless carefully managed.
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