🔍 What is an Elastic Load Balancer?
An Elastic Load Balancer (ELB) is a service from AWS that spreads incoming traffic across multiple servers.
It helps your app stay online, responsive, and fast, even during server failures or traffic spikes.
🌐 Protocols: How ELB Communicates
ELB supports several common internet protocols like
- HTTP (Port 80)
Used for handling regular web traffic.
It’s best when security is not critical. for example, public content that doesn’t need encryption.
- HTTPS (Port 443)
Used for secure web traffic.
It encrypts the data sent between users and your servers, protecting sensitive information.
To use HTTPS, you need to attach an SSL/TLS certificate to your load balancer.
- TCP
Ideal for apps that don’t use HTTP, like chat systems or real-time games.
It gives fast, low-level communication and full control over traffic.
- TLS (formerly SSL)
An upgraded version of TCP that adds encryption.
Useful when you need both speed and security (e.g., secure email, FTP, or custom apps).
- UDP (Supported in Network Load Balancer)
Best for high-performance, real-time applications like video streaming or VoIP.
It’s faster than TCP because it skips error checking, but less reliable.
✅ Which Protocol Should You Use
For websites → Start with HTTP or HTTPS
For apps with high security needs → Use HTTPS or TLS
For real-time apps → Consider TCP or UDP (with a Network Load Balancer)
✅How the ELB works (the basic architecture):
Users send requests to your app.
The ELB receives those requests and forwards them to healthy servers.
It automatically picks the best performing server at that moment.
You should always place your web servers(eg Apache, Nginx)in at least two different Availability Zones to ensure redundancy.
This setup gives your users a smooth experience,even if one server goes down.
✅ How ELB Checks Server Health
The ELB doesn’t just guess which servers work,it runs health checks to know for sure.
It checks if your servers respond correctly.
You control these key settings:
Healthy threshold – how many times a server must pass the check to be marked “healthy”
Unhealthy threshold – how many failed checks before a server is considered “unhealthy”
Response timeout – how long the ELB waits before deciding a server is slow or down
💡 Tip: Make sure your servers return valid responses (like 200 OK) when ELB pings them.
🌐 Accessing Your Website Through ELB
After setting it up:
AWS gives you a DNS name for the ELB (e.g. my-load-balancer-123456.elb.amazonaws.com)
Open that link in your browser
Add your landing page at the end (e.g. /index.html or /index.php)
http://your-elb-dns-name/index.html
This DNS name routes users through the load balancer to your servers.
💡 What Happens If a Server Fails?
If a server crashes, ELB stops sending traffic to it.
It redirects users to a healthy server, without you lifting a finger.
Users won’t even notice something went wrong.
You get high availability especially during peak times.
📌 Final Thoughts
Elastic Load Balancer helps you build resilient and scalable systems, set up your first ELB today.
Hi, My name is Chisom.
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