Networking in AWS centers on the Virtual Private Cloud, or VPC, which lets customers provision a logically isolated section of the AWS cloud. Within a VPC, customers define IP address ranges, create subnets, configure route tables, and attach gateways to control how resources communicate. Because a VPC is logically isolated, traffic between resources in different VPCs is separated just as it would be in different on-premises networks, which gives customers strong control over their network architecture.
A subnet is a range of IP addresses within a VPC and is always associated with a single Availability Zone. Subnets are typically classified as public or private depending on whether they have a route to an Internet Gateway. An Internet Gateway is a horizontally scaled, redundant component that connects a VPC to the public internet, enabling resources in public subnets to send outbound traffic and accept inbound connections. For resources in private subnets that need occasional outbound access, such as for downloading software updates, a NAT Gateway provides Network Address Translation. A NAT Gateway allows instances in a private subnet to reach the internet while preventing unsolicited inbound connections, preserving the security of the private environment.
Elastic Load Balancing, or ELB, automatically distributes incoming application traffic across multiple targets such as EC2 instances, containers, and IP addresses. AWS offers three main types of load balancers, each tuned for a specific use case. The Application Load Balancer, or ALB, operates at the HTTP and HTTPS level and is ideal for web applications that need content-based routing. The Network Load Balancer, or NLB, handles TCP, UDP, and TLS traffic at extreme scale and very low latency. The Gateway Load Balancer, or GWLB, is designed for deploying and scaling third-party virtual appliances such as firewalls and intrusion detection systems.
Beyond the VPC, two services handle global traffic management and content delivery. Amazon Route 53 is a scalable Domain Name System, or DNS, web service that supports domain registration, health checks, and traffic routing policies such as latency-based routing and geolocation routing. Amazon CloudFront is a content delivery network that caches static and dynamic web content at Edge Locations around the world, reducing latency for end users and offloading traffic from origin servers. Together, Route 53 and CloudFront form the outer layer of an AWS network architecture, directing users to the closest, healthiest entry point for an application.