Most sites meet load balancing at a threshold: the sale-day spike, a server that cannot keep up, or a hosting plan that now promises high availability. This page explains how a balancer decides where each request goes, what happens when a server dies, and the signals that say one server is no longer enough.
Load balancing defined — the traffic-cop analogy
Load balancing spreads incoming requests across multiple servers so no single machine carries the load — the traffic cop at the toll plaza, waving each vehicle to the shortest lane.
- Distribution algorithms decide who gets the next request: round-robin, least-connections, or ip_hash.
- Health checks probe each backend and pull failed servers from rotation automatically.
- Failover is the payoff: one server dying becomes a routing change, not an outage.
- Layer 7 balancers read the request itself; Layer 4 balancers route by IP and port.
The sections below walk the mechanism end to end, from algorithm choice to the thresholds that justify the setup.
How algorithms work — round robin, least connections, ip_hash
Algorithms come in two families. Static rules hand out work on a fixed plan and never look at server state; dynamic rules read each server’s condition first. Static is simpler to run but can pile requests onto a slowing machine — dynamic costs more to configure but adapts.
| Algorithm | Rule | Best when |
|---|---|---|
| Round robin | Next request goes to the next server in turn | Similar servers, short requests |
| Weighted round robin | Higher-weight servers receive a bigger share | Mixed hardware in one pool |
| Least connections | Newest request goes to the server with fewest open connections | Requests of uneven length |
| IP hash | A hash of the client IP picks the server | Session stickiness without cookies |
| Least response time | Server with the fastest recent responses wins | Pools with uneven performance |
Health checks and automatic failover
A health check is a periodic probe the balancer sends each server — an HTTP GET to a status endpoint, a TCP connect, or simply watching live traffic for failures. Active checks test availability before traffic arrives; passive checks mark a server down when real connections start failing.
Failover follows: a server that misses its checks stops receiving new requests, and the pool absorbs its share. When it passes checks again, it rejoins the rotation. To the visitor, a dead server looks like nothing at all — no error page, just a routing change.
Layer 4 vs Layer 7 — the practical difference
Layer 4 versus Layer 7 names where in the network stack the balancer operates — and what it can see. Layer 4 (transport): the balancer routes by IP and port without reading the request — fast, protocol-agnostic, unable to make content decisions. Layer 7 (application): the balancer reads HTTP — URLs, headers, cookies — and routes by them: /api/ to the API pool, /images/ to the static pool, cart cookies to a sticky session.
The practical rule: Layer 4 for raw throughput on simple TCP workloads, Layer 7 for anything needing routing intelligence, header manipulation or session persistence. Most web applications want Layer 7, because the intelligence is the feature; the speed difference is real but rarely the deciding factor at the scales where balancing begins.
Sticky sessions for carts and logins
A balancer normally sends each new request wherever the algorithm points, which breaks shopping carts and logins that assume one server holds your session. Sticky sessions pin a client to the server that first served them — by an affinity cookie or the IP hash rule above.
The cleaner long-term fix is a shared session store (Redis or the database) so any server can serve any user, and stickiness stops mattering. Until a store exists, cart and login flows are the workloads that need it.
Load balancer vs CDN vs caching
The three layers solve different problems and often run together:
| Layer | What it does | Where it lives |
|---|---|---|
| Load balancer | Chooses which server handles each request | In front of your server pool |
| CDN | Serves cached copies of static files from edges near the user | A global edge network |
| Cache | Stores computed responses so they are not rebuilt | On each server or in a shared store |
A CDN cuts bytes from the origin, a cache cuts work from the server, and the balancer decides which server survives the traffic that is left. Big sites run all three; the pairing that scales is a cluster behind a balancer — see what server clustering is.
When an Indian business actually needs one
The signals: response times climb during traffic peaks, a single campaign or sale can flatten the site, or an uptime commitment assumes more than one machine. If the workload fits one server, skip the balancer — a bigger VPS is cheaper; compare the options in the cloud vs VPS guide.
When you do need it, cloud hosting is where balancing starts: a pool of servers behind one address with health checks and failover included, scaled on demand. WebJi® sizes and quotes the configuration by email before any payment.
Frequently Asked Questions
What is load balancing in web hosting?
Load balancing spreads incoming requests across multiple servers so no single machine carries the load. The balancer picks a healthy server for every request and removes failed ones from rotation automatically.
How does a load balancer distribute traffic?
It applies a rule — round robin, least connections, IP hash, weighted variants or least response time — to the pool of servers currently passing health checks, and forwards each new request to the chosen machine.
What is the difference between Layer 4 and Layer 7 load balancing?
Layer 4 routes by IP address and port without reading the request; Layer 7 reads HTTP — URLs, headers and cookies — and routes by content. Layer 4 buys raw throughput; Layer 7 buys routing intelligence for web applications.
Do I need a load balancer for my website?
Not while one server fits the workload. You need one when response times climb at peak, a campaign can flatten the site, or an uptime commitment assumes redundancy. Configuration is quoted by email before payment.
What are health checks?
Periodic probes a load balancer sends each server — an HTTP status endpoint, a TCP connect, or passive monitoring of live traffic. Servers that fail their checks stop receiving new requests.
What happens when a server fails behind a load balancer?
The balancer detects the failure through health checks, stops sending that server new requests, and spreads its share across the survivors. Visitors see no error page — the failure becomes a routing change — and the server rejoins when it passes checks again.
Is WebJi® an Indian company?
Yes. WebJi® is headquartered in Jaipur, Rajasthan and has operated since 2005. Billing, support and governance all run from India.
Do you provide GST invoices?
Every purchase and renewal gets a GST invoice with our GSTIN, and hosting prices are quoted exclusive of 18% GST. Claim input credit as applicable.