As per your configuration, put your load balancer in the public subnet(public-facing) and put your web server in a private subnet which will keep them secure.
So in this case, in the future, if you launch instances in the private subnet, it is more secure than launching those instances in public subnets. Also, you can spread your web server across multiple availability zones or you can use Auto Scaling for this purpose which will distribute instances evenly across multiple availability zones and help to meet the demand while minimizing the costs.
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