How does load balancer work? 

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Load balancing improves the distribution of workloads across multiple computing resources, such as servers, computers, a computer clusters, network links, central processing units, disk drives. Load balancing aims are to optimize resource use, maximize throughput, minimize response time, and avoid overload of any single resource. Using multiple components with load balancing instead of a single component may increase reliability and availability through redundancy. Load balancing usually involves dedicated software or hardware, such as a multilayer switch or a Domain Name System server process.

You may use NGINX to set up load balancer used standard approaches. 

Replication is standart, using IP multicast technique. If node is crashed (Out of memory or something else) email will be sent and node will be restarted automatically.