Introduction to `cacheable-lookup`

The `cacheable-lookup` module is a robust and efficient DNS caching library for Node.js applications. By utilizing it, developers can significantly optimize DNS queries and improve application performance. In this post, we’ll dive deep into the `cacheable-lookup` library, explaining its numerous APIs and showcasing practical examples.

API Explanations and Examples

1. Installation

  
  npm install cacheable-lookup
  

2. Basic Usage

  
  const CacheableLookup = require('cacheable-lookup');
  const cacheable = new CacheableLookup();

  // Example
  cacheable.lookup('example.com', (err, address, family) => {
    console.log('address:', address);
    console.log('family:', family);
  });
  

3. Advanced Usage with Got and Https

  
  const got = require('got');
  const https = require('https');
  const CacheableLookup = require('cacheable-lookup');

  const cacheable = new CacheableLookup();
  const agent = new https.Agent({
    lookup: cacheable.lookup
  });

  (async () => {
    const response = await got('https://example.com', { agent });
    console.log(response.body);
  })();
  

4. Configuring CacheableLookup

  
  const cacheable = new CacheableLookup({
    maxTtl: 60,      // Maximum time to live in seconds
    minTtl: 10,      // Minimum time to live in seconds
    errorTtl: 0.5    // Time to live for errors in seconds
  });
  

5. Clear Cache

  
  cacheable.cache.clear();
  

Application Example

Here’s a complete example of how `cacheable-lookup` can be integrated into a Node.js application to improve DNS resolution efficiency.

  
  const http = require('http');
  const CacheableLookup = require('cacheable-lookup');

  const cacheable = new CacheableLookup();
  const server = http.createServer((req, res) => {
    cacheable.lookup('example.com', (err, address) => {
      if (err) {
        res.writeHead(500);
        res.end('Error with DNS lookup');
      } else {
        res.writeHead(200, { 'Content-Type': 'text/plain' });
        res.end('Resolved Address: ' + address);
      }
    });
  });

  server.listen(3000, () => {
    console.log('Server running at http://localhost:3000/');
  });
  

By integrating `cacheable-lookup`, your applications can benefit from quicker DNS resolutions, ensuring smoother and more efficient network operations.

Conclusion

`cacheable-lookup` is a highly beneficial library for Node.js developers, offering advanced DNS caching capabilities. With this guide, you should be able to integrate it into your own projects effectively.

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