Is a load balancer node a bottleneck?

Question

in a web application and service I'm creating it's necessary that it scales horizontally. I want to have 1 load balancer, 3 web server nodes, and 2 database nodes (one will be solely for redundancy and will scale vertically as soon as the first db node goes down).

1. Does the load balancer act as a proxy?
2. If so doesn't that defeat the purpose of scaling horizontally if it's going to be a massive bottle-neck?
3. Should it have significantly more resources than the web server nodes?

Answer 1

[I think you meant "scales horizontally" in your first sentence.]

1. Yes, typical load balancers are proxys.
2. The load balancer will be a bottleneck if your load is network bound. Usually load is CPU bound so the load balancer distributes the CPU load, not the network load.
3. No. load balancers don't need many resources since they don't hold or process much data. It should have as much network resources (bandwidth) as possible however.