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