- Operates at Layer 4 (Transport layer)
- Handles TCP and UDP traffic with extremely low latency
- Designed for millions of requests per second and high-throughput workloads
- Ideal for performance-critical applications or when TCP/UDP is required
Key Features
- Provides one static IP per Availability Zone
- Can associate Elastic IPs for static addressing and IP whitelisting
- Supports cross-zone load balancing (optional)
- Integrated with AWS services like EC2, ECS, and PrivateLink
- Not part of the AWS Free Tier
Routing & Target Groups
- Routes traffic based on TCP or UDP rules
- Target group types:
- EC2 instances
- Private IP addresses
- Application Load Balancers (chaining ALB behind NLB)
- Health checks can use TCP, HTTP, or HTTPS
Example use cases:
- Low-latency financial applications
- Real-time multiplayer games
- Hybrid connectivity with on-prem services via Private IPs
- Static IP requirement for clients
Routing behavior note:
When a target group is of type EC2 instance, the NLB always routes traffic to theprimary private IP address of the instance’s primary network interface (eth0), even if the instance has a public IP or Elastic IP.