Interview Q&A / AWS & Cloud

1. How do an Auto Scaling group and a load balancer work together on AWS?

   An Auto Scaling group keeps the right number of healthy EC2 instances running, adding or removing them based on policies such as target CPU. A load balancer spreads incoming traffic across those instances in multiple AZs. The ASG registers new instances with the load balancer's target group and replaces any that fail health checks.

   AdvancedIn-depth4 min read
2. What are the types of Elastic Load Balancer and when do you use each?

   Application Load Balancer works at layer 7 for HTTP and HTTPS with path and host routing. Network Load Balancer works at layer 4 for TCP, UDP and TLS with very high performance and static IPs. Gateway Load Balancer fronts network appliances. Classic is legacy.

   BeginnerQuick answer1 min read
3. How does an Application Load Balancer route requests to different services?

   An ALB listener evaluates rules in priority order. Each rule has conditions, such as path, host header, HTTP header or query string, and an action, usually forward to a target group. A default rule catches everything else.

   IntermediateQuick answer1 min read