How to distinguish Network Load Balancer from Application Load Balancer and what are their main differences?
sobes.tech AI
Answer from AI
Network Load Balancer (NLB) and Application Load Balancer (ALB) are two types of load balancers that differ in the OSI model layer they operate at and their intended purpose.
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Network Load Balancer (NLB) operates at layer 4 (transport layer). It balances TCP/UDP traffic, providing high performance and low latency. NLB is suitable for applications where speed and scalability are important, such as database load balancing, VoIP, gaming servers.
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Application Load Balancer (ALB) operates at layer 7 (application layer). It understands HTTP/HTTPS protocols and can make routing decisions based on request content (e.g., URL, headers, methods). ALB is suitable for web applications that require intelligent routing and support for modern web protocols.
Main differences:
| Characteristic | Network Load Balancer (NLB) | Application Load Balancer (ALB) |
|---|---|---|
| OSI Layer | 4 (transport) | 7 (application) |
| Protocol Types | TCP, UDP | HTTP, HTTPS |
| Routing | By IP and port | By HTTP request content (URL, headers) |
| SSL Support | SSL passthrough (usually) | SSL termination and certificate management |
| Usage | High-performance services where speed is crucial | Web applications with complex routing logic |
Example: if you need to balance a simple TCP service (e.g., a database), choose NLB. If you need to route requests to different microservices based on URL, choose ALB.