node-dnslookup

Improve your dns lookup in NodeJS, more customizable.

Features

• DNS cache in memory
• Local hosts map like /etc/hosts
• Use specific DNS servers

Usage

Install via npm.

npm install --save node-dnslookup

Quck examples:

const ns = require('node-dnslookup');

https.request('example.org', {
    lookup: ns.lookup,
});

// Apply to all requests
ns.use(https.globalAgent);

// With options
new ns.DNSLookup(options).lookup
// Or
ns.use(agent, options);

Options table:

|property|description|default|example| |-|-|-|-| |hosts|self-defined local hosts|[]|['127.0.0.1 local localhost', '::1 ipv6.local']| |servers|DNS servers. Useful for private network|[]|['8.8.8.8']|

More

Inspired by cacheable-lookup; Related post: Fixing DNS in Node.js.

Reason

The native dns.lookup is implemented as a synchronous call on libuv's threadpool. So when you have a lot of network requests in short time, the process may be blocked becauseof DNS lookups, even causes itself or other unrelated node scripts hang up and be a "zombie" process.

No benchmark data proves better performance in production, but it theoretically does. It's not recommanded if no problems come with you.

Benchmarks

┌──────────────┬─────────┬─────────┬──────────┬────────┬────────┬──────────┬─────────┬───────────┬───────────┐
│   function   │    N    │   #1    │   max    │  min   │  avg   │ >10ms(%) │ >1ms(%) │ >0.1ms(%) │ faster(%) │
├──────────────┼─────────┼─────────┼──────────┼────────┼────────┼──────────┼─────────┼───────────┼───────────┤
│ 'dns.lookup' │ 1000000 │ 11.9297 │ 361.3681 │ 0.1868 │ 0.2596 │  0.0203  │ 0.6732  │  99.3064  │           │
│  'ns.lookup' │ 1000000 │ 14.0073 │ 110.6485 │ 0.0004 │ 0.0009 │  0.0001  │ 0.0053  │   0.0103  │  99.986   │
└──────────────┴─────────┴─────────┴──────────┴────────┴────────┴──────────┴─────────┴───────────┴───────────┘
Total: 26:19.123 (m:ss.mmm)

Indicators|description -|- "N" | run times "#1" | average cost time of every hostname first lookup "max" | maximum lookup cost time exclude the first "min" | minimum lookup cost time exclude the first "min" | average lookup cost time exclude the first "faster(%)" | (count of cost time that less than dns.lookup minimum value) / total