System Design - Load Balancer

Question 1

Where are load balancers typically added?

Answer 1

• Between the user and web servers
• Between web servers and an internal platform layers like application servers or cache servers
• Between an internal platform layer and the database lately

Question 2

Load Balancing Algorithms

Answer 2

• Health check. Doesn’t send traffic to unhealthy servers.
• Direct traffic to the server with the fewest connections
• Direct traffic to the server with the lowest average response time
• Direct traffic to the server serving the least amount of data Mbps
• Round Robin (works in situations where servers are all alike and there aren’t many persistent connections)
• Weighted Round Robin - Designed to handle servers with different processing capacities

Question 3

Load Balancer Progression

Answer 3

• Start with software load balancer (HA proxy; locally bound to port and distributed traffic) move to smart clients (client application) then to hardware (even by $ companies only used as first point of contact with the system).