[Solved] Why does an Application Load Balancer not support UDP traffic, while a Network Load Balancer does? — Ans: ALB operates at Layer 7 (application layer) which is protocol-specific, NLB... | AWS

AWS - Elastic Load Balancing

Why does an Application Load Balancer not support UDP traffic, while a Network Load Balancer does?

AALB is designed for legacy protocols only, NLB is for modern protocols

BALB is limited to TCP only due to AWS policy, NLB has no such restrictions

CALB requires SSL termination which UDP does not support, NLB does not terminate SSL

DALB operates at Layer 7 (application layer) which is protocol-specific, NLB operates at Layer 4 (transport layer) supporting UDP

Step-by-Step Solution

Solution:

Step 1: Understand OSI layers for ALB and NLB
ALB works at Layer 7 (application layer), handling HTTP/HTTPS protocols.
Step 2: NLB operates at Layer 4
NLB works at Layer 4 (transport layer), supporting TCP and UDP protocols.
Final Answer:
ALB operates at Layer 7 (application layer) which is protocol-specific, NLB operates at Layer 4 (transport layer) supporting UDP -> Option D
Quick Check:
ALB Layer 7, NLB Layer 4 = UDP support [OK]

Quick Trick: ALB = Layer 7, no UDP; NLB = Layer 4, supports UDP [OK]

Common Mistakes:

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Why does an Application Load Balancer not support UDP traffic, while a Network Load Balancer does?