1import { Agent, fetch } from 'undici';23// Create a custom Agent with DNS configuration4const agent = new Agent({5  connect: {6    // Set DNS lookup timeout (in milliseconds)7    lookupTimeout: 1000,8    9    // Set DNS lookup algorithm (ipv4first, verbatim, or happy eyeballs)10    // - ipv4first: Try IPv4 addresses first, then IPv611    // - verbatim: Use addresses in the order provided by the DNS resolver12    // - happy eyeballs: Try both IPv4 and IPv6 simultaneously with a small delay13    lookupAlgorithm: 'ipv4first',14    15    // Set DNS lookup family (can be 0 for both IPv4 and IPv6, 4 for IPv4 only, or 6 for IPv6 only)16    family: 0,17    18    // Optional: Custom DNS resolver function19    lookup: (hostname, options, callback) => {20      console.log(`Custom DNS lookup for: ${hostname}`);21      // For demonstration, we'll use the default Node.js DNS lookup22      // In a real implementation, you could use a custom DNS server or cache here23      const dns = require('dns');24      dns.lookup(hostname, options, callback);25    }26  },27  28  // Connection timeout in milliseconds29  connectTimeout: 5000,30  31  // Maximum number of connections per origin32  connections: 1033});3435async function makeRequest() {36  console.log('Making request with custom DNS resolution...');37  38  try {39    // Use the custom agent for fetch40    const response = await fetch('https://example.com', { 41      dispatcher: agent 42    });43    44    const text = await response.text();45    console.log(`Response status: ${response.status}`);46    console.log(`Response size: ${text.length} bytes`);47    console.log(`First 100 characters: ${text.substring(0, 100)}...`);48    49    // Get connection information50    console.log('\nConnection Information:');51    console.log(`Protocol: ${response.headers.get('x-forwarded-proto') || 'https'}`);52    console.log(`Server: ${response.headers.get('server')}`);53    54  } catch (error) {55    console.error('Request failed:', error);56  } finally {57    // Close the agent when done to clean up connections58    await agent.close();59  }60}6162// Execute the request63makeRequest();