Load Balancing

Nginx Cheat Sheet

Core Nginx configuration syntax for serving static files, reverse proxying, load balancing, and TLS termination.

What is Hash-Based Sharding?

Hash-based sharding applies a hash function to the shard key and uses the result (typically modulo the shard count) to assign each row to a shard, which spread…

What is Consistent Hashing and Why Do Databases Use It?

Consistent hashing maps both shard keys and shard servers onto the same circular hash space, so each key is owned by the next server found clockwise on the rin…

How Does Load Balancing Across Database Replicas Work?

Load balancing across database replicas is the practice of distributing read queries across multiple replica servers using a strategy such as round robin, leas…

What is Consistent Hashing and Why is it Used?

Consistent hashing maps both keys and servers onto the same circular hash ring so that when a server is added or removed, only the keys between it and its neig…

What is Load Balancing in a Multiprocessor OS?

Load balancing in a multiprocessor OS is the scheduler policy of spreading runnable tasks evenly across all available CPU cores so no core sits idle while anot…

What Are the Key Challenges in Multicore Scheduling?

Multicore scheduling is harder than single-core scheduling because the OS must simultaneously reason about cache locality, load balancing across cores, synchro…

What is a Proxy Server?

A proxy server is an intermediary that sits between a client and the destination server, forwarding requests and responses on the client’s behalf while optiona…

DNS Load Balancing Explained

DNS load balancing spreads traffic across multiple servers by having the DNS server return different IP addresses for the same hostname to different clients or…

What is Equal-Cost Multipath (ECMP)?

Equal-Cost Multipath (ECMP) is a routing technique where a router installs and actively uses multiple paths to the same destination in its forwarding table sim…

What is GLBP (Gateway Load Balancing Protocol)?

GLBP (Gateway Load Balancing Protocol) is a Cisco-proprietary first-hop redundancy protocol that, unlike HSRP or VRRP, actively load-balances outbound traffic…

What is a Reverse Proxy?

A reverse proxy is a server that sits in front of one or more backend servers and accepts client requests on their behalf, forwarding each request to an approp…

Forward Proxy vs Reverse Proxy: What is the Difference?

A forward proxy sits in front of clients and hides the client’s identity from the servers it connects to, while a reverse proxy sits in front of servers and hi…

What is Geo Load Balancing?

Geo load balancing routes each client request to the nearest or best-performing data center or region based on the client’s geographic location, typically usin…

What is a Load Balancer Algorithm?

A load balancer algorithm is the rule a load balancer uses to decide which backend server receives each incoming request — common examples include round robin,…

Round Robin vs Least Connections Load Balancing

Round robin distributes requests to backend servers in a fixed rotating order regardless of current load, while least connections sends each new request to whi…

What is Health Checking in Networking?

Health checking is the process by which a load balancer or orchestrator periodically probes each backend server — via TCP connect, HTTP request, or a custom pr…

What is Session Persistence?

Session persistence (also called sticky sessions) is a load balancer feature that routes all requests from a given client to the same backend server for the du…

What is Load Balancing?

Load balancing is the practice of distributing incoming network traffic across multiple backend servers so no single server is overwhelmed, improving availabil…

Horizontal vs Vertical Scaling

Vertical scaling (scaling up) means adding more power — CPU, RAM or disk — to a single machine, while horizontal scaling (scaling out) means adding more machin…

What is a Reverse Proxy?

A reverse proxy is a server that sits in front of one or more backend servers and forwards client requests to them, returning the response back to the client a…

What are Sticky Sessions in Load Balancing?

Sticky sessions (session affinity) are a load balancer configuration that routes all requests from a given client to the same backend server for the duration o…

What Are the Main Data Partitioning Strategies?

Data partitioning splits a large dataset across multiple nodes using a strategy such as range partitioning (contiguous key ranges per node), hash partitioning…

What is Service Discovery in Microservices?

Service discovery is the mechanism by which services in a distributed system automatically find the current network location of other services, since instances…

How Do WebSockets Scale in a Distributed System?

WebSockets scale in a distributed system by keeping the persistent connection itself pinned to one server while offloading cross-server message delivery to a s…