Infrastructure
DNS, CDNs, Load Balancers, and Reverse Proxies.
- Explain the roles of DNS and CDN in the request flow.
- Distinguish between Layer 4 and Layer 7 load balancing.
- Identify security benefits of using a reverse proxy.
- Design a basic topology using a load balancer for redundancy.
01 DNS and CDN: User Entry Points Viz
DNS
The internet's phone book that matches domain names with server IP addresses.
CDN
A collection of servers across various geographic locations to speed up content delivery.
Use a CDN for all static assets. Some modern CDNs can even help speed up dynamic content through network path optimization.
Latency reduction
Reducing wait time by bringing data closer to the user.
Edge Computing
Running logic or storing data on the server closest to the user (the 'edge').
02 Load Balancer: System Traffic Police
- **SSL Termination**: The load balancer can handle HTTPS encryption so the servers behind it are not burdened.
- **Health Checks**: The load balancer automatically stops sending traffic to servers that are currently failing.
- **Session Persistence**: Ensuring that the same user is always directed to the same server (if necessary).
Load Balancers eliminate 'Single Points of Failure'.Deeper InsightWith multiple servers, your system will not go down completely just because one computer fails. Click to collapse
03 Reverse Proxy vs. Load Balancer
| Feature | Load Balancer | Reverse Proxy |
|---|---|---|
| Main Goal | Load distribution | Access control & Security |
| Scale | Requires many servers | Can be for just 1 server |
| Examples | F5, AWS ELB | Nginx, Apache |
Comparison of Load Balancer and Reverse Proxy.
In modern architectures, Nginx is often used as both a reverse proxy and a software-layer load balancer.
Key Takeaways
- 1CDNs are the easiest way to reduce global latency.
- 2Load balancers are essential for High Availability.
- 3Reverse proxies protect internal infrastructure from direct public access.
- 4Health checks in load balancers automatically handle failed servers.
CH.02
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Infrastructure Quiz
Test your understanding of DNS, CDN, Load Balancers, and Reverse Proxies.
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