Decoding the Cloud
AWS networking lets you build a private, secure network in the cloud with a VPC, direct traffic with Route 53, and deliver content quickly to users worldwide with CloudFront.
AWS Networking and Content Delivery
Every application you use depends on a network moving data between machines. In the cloud, you don't buy cables or routers. You design the network in software. Module 5 of AWS Academy Cloud Foundations covers how that works, from the basics of networking to delivering content to users around the world.
Networking Basics
A network is a group of computers that can communicate with each other.
- IP addresses: every device on a network has an address. IPv4 addresses look like 192.0.2.10, and IPv6 gives a much larger address space.
- CIDR notation: this describes a range of addresses. For example, 10.0.0.0/16 means a block of about 65,000 addresses. The number after the slash tells you how large the block is (a smaller number means a bigger block).
- OSI model: a seven-layer way of thinking about how data travels, from physical cables up to applications. You mostly work at the network layer (IP) and the transport layer (TCP/UDP).
Amazon VPC
An Amazon Virtual Private Cloud (VPC) is your own private, isolated section of the AWS cloud. You decide its IP range, divide it into smaller pieces and control what can enter or leave. Its main parts are:
- Subnets: smaller segments of the VPC, each living in one Availability Zone. A public subnet can reach the internet, while a private subnet can't be reached directly from it.
- Internet gateway: the door that connects your VPC to the internet.
- NAT gateway: lets resources in a private subnet make outbound requests, such as downloading updates, without letting the internet reach them.
- Route tables: rules that tell network traffic where to go.
A common design puts web servers in a public subnet and databases in a private one. Visitors can reach the website, but nobody can reach the database directly.
The VPC Wizard
The console demonstration shows how the VPC wizard saves effort. Instead of creating every piece by hand, you pick a configuration, such as a VPC with public and private subnets, and the wizard builds the subnets, gateways and route tables in a few clicks. It's a good way to see how all the pieces fit together before building them manually.
VPC Networking
Once your VPC exists, you can connect it to other places:
- Elastic IP addresses: fixed public IPv4 addresses that stay with your account, so the address doesn't change when an instance restarts.
- Elastic network interfaces (ENIs): virtual network cards you can attach to instances.
- VPC peering: a direct private connection between two VPCs, so they can talk without going over the public internet.
- VPC endpoints: private access to AWS services like S3 without traveling over the internet.
- AWS Site-to-Site VPN and AWS Direct Connect: ways to link your VPC to an office or on-premises data center. A VPN uses an encrypted tunnel over the internet, while Direct Connect uses a dedicated private line.
- AWS Transit Gateway: a central hub that connects many VPCs and networks, so you don't have to peer each pair separately.
Amazon Route 53
Route 53 is AWS's highly available Domain Name System (DNS) service. DNS turns names people can remember, like example.com, into the IP addresses computers use. Route 53 also lets you register domains and check the health of your resources. It supports different routing policies:
- Simple: sends traffic to one resource.
- Weighted: splits traffic by percentage, which is useful for testing a new version.
- Latency-based: sends users to the region that responds fastest.
- Failover: switches to a backup when the main resource is unhealthy.
- Geolocation: routes based on where the user is.
Amazon CloudFront
CloudFront is a content delivery network (CDN). It stores copies of your content, such as images, videos and web pages, in edge locations around the world. When a user requests something, it's served from the nearest edge location instead of your origin server, which means faster load times, lower latency and less load on your servers. CloudFront also works with AWS Shield and AWS WAF to help protect against attacks.
Conclusion
Good cloud networking comes down to a few clear decisions: who can reach what, how traffic finds its way, and how quickly users get what they asked for. VPC gives you the structure, security groups and network ACLs give you protection, Route 53 gives you direction, and CloudFront gives you speed.
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