5) Elastic Load Balancing (ELB) & Auto Scaling Groups (ASG)

A set of vocabulary flashcards defining key concepts, load balancer types, and scaling strategies from the lecture notes.

Scalability

The capability of an application or system to handle greater loads by adapting.

Vertical Scalability

Increasing the size of an individual instance, such as moving an application from a t2.micro to a t2.large instance.

Horizontal Scalability

Increasing the number of instances or systems running an application, which implies using distributed systems.

High Availability

Running an application or system across at least two Availability Zones to survive data center loss or disaster.

Elasticity

The automatic scaling of a system based on real-time load once scalability is established.

Agility

A cloud feature where new IT resources are available with a click, reducing resource deployment time for developers from weeks to minutes.

Load Balancer

A server that forwards internet traffic across multiple downstream EC2 instances to distribute load, handle instance failures, conduct health checks, and provide SSL termination.

Elastic Load Balancer (ELB)

A managed load balancer offered by AWS that guarantees operation and handles upgrades, maintenance, and high availability.

Application Load Balancer (ALB)

An AWS Layer 7 load balancer supporting HTTP, HTTPS, and gRPC protocols with HTTP routing features and a static DNS URL.

Network Load Balancer (NLB)

An AWS Layer 4 load balancer supporting TCP and UDP protocols, capable of ultra-high performance handling millions of requests per second with static Elastic IPs.

Gateway Load Balancer (GWLB)

An AWS Layer 3 load balancer operating on the GENEVE protocol on IP packets to route traffic to third-party security virtual appliances and firewalls.

Classic Load Balancer (CLB)

A legacy AWS load balancer operating at Layer 4 and Layer 7 that was retired in 2023.

Auto Scaling Group (ASG)

An AWS service designed to scale out or scale in EC2 instances to match changing demand, enforce machine boundaries, replace unhealthy instances, and automatically register new instances to a load balancer.

Dynamic Scaling

An Auto Scaling strategy that automatically responds to changing demand, including Simple/Step Scaling via CloudWatch alarms and Target Tracking Scaling.

Target Tracking Scaling

A dynamic scaling strategy that maintains a specific metric at a designated target, such as keeping average ASG CPU utilization around 40%.

Scheduled Scaling

An Auto Scaling strategy that adjusts instance capacity according to known and predictable usage patterns over time.

Predictive Scaling

An Auto Scaling strategy that uses Machine Learning to forecast traffic ahead of time and automatically provision EC2 instances in advance.