Let’s get a quick overview of Elastic Load Balancers from an AWS certification perspective. We will look at important certification questions regarding Elastic Load Balancers - Application Load Balancer vs Network Load Balancer vs Classic Load Balancer (ALB vs NLB vs CLB).
You will learn
- What are the different Elastic Load Balancers offered by AWS?
- How do they compare - Application Load Balancer vs Network Load Balancer vs Classic Load Balancer (ALB vs NLB vs CLB)?
- How do you choose - Application Load Balancer vs Network Load Balancer vs Classic Load Balancer (ALB vs NLB vs CLB)?
AWS Certification - 25 PDF Cheat Sheets + Free Course
Each cheat sheet contains:
- FAQs and Tutorials with 5-20 slides
- Notes to quickly review and prepare for certification exam
- Certification Exam Tips
- Certification and Interview Scenario Questions
ALB vs NLB vs CLB
Here’s a table comparing the features of different load balancers. You can find details about these features below the table.
|Feature||Application Load Balancer||Network Load Balancer||Classic Load Balancer|
|Version||New v2||New v2||Old v1|
|Use cases||Web apps, microservices & containers||Extreme performance - millions of requests with less latency (100ms)||Avoid if possible. Not recommended by AWS.|
|Protocols Supported||HTTP, HTTPS (Layer 7)||TCP, UDP, TLS (Layer 4)||TCP, SSL/TLS, HTTP, HTTPS(Layer 4 & 7)|
|Dynamic Host Port Mapping||✓||✓|
|Cross-zone load balancing||✓(Always Enabled)||✓(Default Disabled)||✓(Default Disabled)|
|Server Name Indication (SNI)||✓||✓|
|Elastic IP address||✓|
|Preserve Source IP address||✓|
|IP addresses as targets||✓||✓ (TCP, TLS)|
|Source IP address range (CIDR) based routing||✓|
|Path(Route) Based Routing||✓|
|Lambda functions as targets||✓|
|HTTP header-based routing||✓|
|HTTP method-based routing||✓|
|Query string parameter-based routing||✓|
Elastic Load Balancer Terminology
Here is some of the important terminology referred to in the above table:
- Connection draining - Before an instance is terminated, requests in execution are given time to complete (deregistration_delay.timeout_seconds)
- Dynamic Host Port Mapping - Useful with containers. Two instances of the same task can be running on the same ECS container instance
- Cross-zone load balancing - Distribute load between available instances in multiple AZs in One Region
- Sticky sessions - Send requests from same user to same instance (cookies with configurable expiration - Stickiness duration default - 1 day)
- Preserve Source IP address - Allows instances to know where the request is coming from
- WebSockets - Allows full-duplex communication over a single TCP connection
- Source IP range (CIDR) based routing - Redirect to different targets based on the Source CIDR block
- Path(Route) Based Routing - Send traffic to different targets based on the path of the request
- Query string parameter-based routing - /user?target=target1 vs /user?target=target2
- Server Name Indication (SNI) - Support multiple websites with different SSL certificates with one Load Balancer