Merge pull request #224317 from aimee-littleton/patch-122

update snat port explanation

Author: prmerger-automator[bot]

articles/virtual-network/nat-gateway/nat-gateway-resource.md

@@ -164,7 +164,7 @@ NAT gateway dynamically allocates SNAT ports across a subnet's private resources
 
 *Figure: Virtual Network NAT on-demand outbound SNAT*
 
-Pre-allocation of SNAT ports to each virtual machine isn't required, which means SNAT ports aren't left unused by VMs not actively needing them.
+Pre-allocation of SNAT ports to each virtual machine is required for other SNAT methods. This pre-allocation of SNAT ports can cause SNAT port exhaustion on some virtual machines while others still have available SNAT ports for connecting outbound. With NAT gateway, pre-allocation of SNAT ports isn't required, which means SNAT ports aren't left unused by VMs not actively needing them.
 
 :::image type="content" source="./media/nat-overview/exhaustion-threshold.png" alt-text="Diagram of all available SNAT ports used by virtual machines on subnets configured with NAT and an exhaustion threshold.":::