Skip to main content

How do you create a simple HTTP server using Node.js?

You can create a simple HTTP server in Node.js using the built-in http module — no external libraries required. Here's a minimal example:

Step-by-Step: Create a Simple HTTP Server

// 1. Import the http module const http = require('http'); // 2. Define the server logic const server = http.createServer((req, res) => { res.statusCode = 200; // HTTP OK res.setHeader('Content-Type', 'text/plain'); res.end('Hello, world!\n'); // Response body }); // 3. Start listening on a port const PORT = 3000; server.listen(PORT, () => { console.log(`Server running at http://localhost:${PORT}/`); });

πŸ” How It Works:

  • http.createServer() creates an HTTP server and defines how it handles requests (req) and responses (res).

  • res.end() sends the response to the client.

  • server.listen() starts the server on a specific port (e.g., 3000).

✅ To Run the Server:

  1. Save the code as server.js

  2. Run in your terminal:

    node server.js
  3. Visit http://localhost:3000 in your browser — you’ll see "Hello, world!"

Popular posts from this blog

How does BGP prevent routing loops? Explain AS_PATH and loop prevention mechanisms.

 In Border Gateway Protocol (BGP), preventing routing loops is critical — especially because BGP is the inter-domain routing protocol used to connect Autonomous Systems (ASes) on the internet. πŸ”„ How BGP Prevents Routing Loops The main mechanism BGP uses is the AS_PATH attribute . πŸ” What is AS_PATH? AS_PATH is a BGP path attribute that lists the sequence of Autonomous Systems (AS numbers) a route has traversed. Each time a route is advertised across an AS boundary, the local AS number is prepended to the AS_PATH. Example: If AS 65001 → AS 65002 → AS 65003 is the route a prefix has taken, the AS_PATH will look like: makefile AS_PATH: 65003 65002 65001 It’s prepended in reverse order — so the last AS is first . 🚫 Loop Prevention Using AS_PATH ✅ Core Mechanism: BGP routers reject any route advertisement that contains their own AS number in the AS_PATH. πŸ” Why It Works: If a route makes its way back to an AS that’s already in the AS_PATH , that AS kno...

What’s the impact of BGP full routes on router memory and performance?

Receiving full BGP routes (i.e., the full global BGP routing table) has a significant impact on a router's memory and performance. Here's a breakdown of the key impacts: πŸ”§ 1. Memory Usage (RAM) A full BGP table typically contains ~1 million IPv4 routes and growing (~200k+ IPv6 routes). Each BGP route consumes tens to hundreds of bytes of memory, depending on attributes (AS path, communities, etc.). This translates to hundreds of megabytes to several gigabytes of RAM just for storing the BGP RIB (Routing Information Base). The FIB (Forwarding Information Base) , which is installed into the router's hardware or kernel for actual packet forwarding, also consumes memory (especially in TCAM for hardware routers). ❗ Example A router might require 4–8 GB of RAM (or more) to comfortably handle full BGP routes with headroom for growth and stability. 🧠 2. CPU Utilization High CPU load during: Initial BGP session establishment (parsing all rout...

Explain the OSPF LSDB (Link State Database) and how SPF (Shortest Path First) algorithm works.

OSPF (Open Shortest Path First) is a link-state routing protocol , and the LSDB (Link-State Database) and SPF (Shortest Path First) algorithm are core to how OSPF calculates the best paths . Let’s break them down. 🧠 What is the OSPF LSDB (Link-State Database)? The LSDB is a map of the entire OSPF network area — each router stores a complete topology of its area. πŸ” Details: Built from LSAs (Link-State Advertisements) exchanged between routers. Contains info about: Routers and their interfaces Network segments Neighbor relationships Each OSPF router maintains an identical LSDB within the same area. ✅ Key Characteristics: Feature Description Scope One LSDB per OSPF area Source Built from received LSAs Consistency All routers in an area have identical LSDBs Purpose Used as input for SPF algorithm to calculate best paths ⚙️ How the SPF Algorithm Works in OSPF OSPF uses Dijkstra’s Shortest Path First (SPF) algorithm to compute the shortest (lowest-cost)...