dns.js

const fs = require('fs');
const dns = require('dns');

const args = process.argv.slice(2)
const hostname = args[0]

fs.readFile('/etc/resolv.conf', (err, data) => {
    if (err) {
        console.dir(err);
    } else {
        console.log('resolv.conf:\n%s', data);
    }
});

dns.resolveAny(hostname, (err, addresses) => {
    if (err) {
        console.error(err);
    } else {
        addresses.forEach((value) => {
            console.log('resolve %s: %s', hostname, value);
        })
    }
})

dns.lookup(hostname, {family: 4}, (err, addr, family) => {
    if (err) {
        console.error(err);
        process.exit(1);
    }
    console.log('lookup %s: %s AF %d', hostname, addr, family);
    process.exit(0);
})