NETWORKING / A CONCEPT NOTE
Load Balancers
distributing traffic across servers to keep things fast and reliable
Overview · mechanism
pitfall · examples
01 / THE SHORT VERSION
The idea in a few sentences.
A load balancer sits in front of a group of servers and distributes incoming requests across them using algorithms like round-robin, least connections, or IP hash. It also runs health checks — if a server goes down, traffic stops going to it. Cloud LBs (ALB, NLB, GLB) scale transparently and terminate TLS.
02 / FOLLOW THE MECHANISM
How a load balancer routes traffic
Client
sends a request to the load balancer's DNS name or IP.
Load Balancer
terminates TLS (if HTTPS), inspects the request, and picks a target based on its algorithm.
Health check
the LB has already verified which targets are healthy via periodic HTTP or TCP checks.
Target server
receives the request, processes it, and sends the response back through the LB.
Stickiness
optional — if sessions need to persist, the LB sets a cookie to pin the client to the same target.
04 / COMMAND NOTES
Read the command, then the result.
Inspect the flags and arguments before trying an example. Snippets can need local setup, replacement values, or resources in your own environment.
list all target groups and health status
aws elbv2 describe-target-groupsinspect LB response headers
curl -I https://your-alb-dns.us-east-1.elb.amazonaws.com05 / CHECK YOURSELF
Could you explain Load Balancers to a teammate?
Try it out loud in two sentences: what it is, and the one detail that changes the picture. If you stall, the gap is the part to reread.
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