1. Distribute load to difference server. Could be in L4 and L7 layer, TCP/IP, HTTP, etc.
2. Check which server is available and redirect works.  ### Algorithms:
1. Round Robin
2. Round Robin with weighted server
3. Least connections
4. Least Response Time
5. Source IP Hash
6. URL hash ### Benefit:
1. prevent request goes to unhealthy server
2. prevent overloading server
3. eliminate single point of failure