Added

README.md

@@ -13,7 +13,7 @@ Uses `dig` command to make DNS requests, has a built-in list of subdomains to te
 Aiming to have these features:
 - [x] Retrieve DNS records for a domain -> `dnsRecords.getDnsRecords()`
 - [x] Discover common subdomains for a domain -> `dnsRecords.getAllRecords()`
-- [ ] Test that all NS respond with same info
+- [ ] Test that all NS respond with same info, with extra info: response time, NameServer location & ISP
 
 ## Getting Started
 
@@ -97,6 +97,40 @@ Returns a promise which resolves with an `Array` of records found, grouped by ty
 }
 ```
 
+**Test NS servers for a domain**
+```js
+const dnsRecords = require('./index.js');
+
+(async () => {
+
+  // Discover NS info
+  const NSRecords = await dnsRecords.getNameServers('fb.com')
+  console.log('NS servers info', NSRecords)
+
+})()
+```
+Returns a promise which resolves with an `Array` of NS info:
+```js
+[
+  {
+    ns: 'a.ns.facebook.com.',
+    soaSerial: '1565080527',
+    IPv4: [ '69.171.239.12' ],
+    IPv6: [ '2a03:2880:fffe:c:face:b00c::35' ],
+    responseTimev4: '',
+    responseTimev6: ''
+  },
+  {
+    ns: 'b.ns.facebook.com.',
+    soaSerial: '1565080527',
+    IPv4: [ '69.171.255.12' ],
+    IPv6: [ '2a03:2880:ffff:c:face:b00c::35' ],
+    responseTimev4: '',
+    responseTimev6: ''
+  }
+]
+```
+
 ## More
 
 Please report any issues here on GitHub.

index.js

@@ -88,6 +88,58 @@ const getDnsRecords = async (names, types, server) => {
 	return re
 }
 
+
+const getNameServers = async domain => {
+	let ns = []
+
+	if (!isDomain(domain)) {
+		throw new Error(`"${domain}" is not a valid domain name`)
+	}
+
+	const nameServers = await getDnsRecords(domain, 'NS')
+
+	if (!nameServers.length) {
+		throw new Error(`No name servers found for "${domain}"`)
+	}
+
+	nameServers.forEach(nameServer => {
+		ns.push({
+			ns:				nameServer.value,
+			soaSerial:		'',
+			IPv4:			[],
+			IPv6:			[],
+			responseTimev4:	'',
+			responseTimev6:	''
+		})
+	})
+
+
+	// get SOA Record 
+	const SOA = await Promise.all(ns.map(nameServer => getDnsRecords(domain, 'SOA', nameServer.ns)))
+	SOA.forEach((records, index) => {
+		const soaRecord = records[0].value.split(' ')
+		ns[index].soaSerial = soaRecord[2]
+	})
+
+
+	// get A/AAAA Records
+	const A = await Promise.all(ns.map(nameServer => getDnsRecords(nameServer.ns, ['A', 'AAAA'])))
+	A.forEach((records, index) => {
+		records.forEach(record => {
+			const ip = record.type === 'A' ? 'IPv4' : 'IPv6'
+			ns[index][ip].push(record.value)
+		})
+	})
+
+
+	// TODO get IPs response time
+	// https://wp-rocket.me/blog/test-dns-server-response-time-troubleshoot-site-speed/
+
+
+	return ns
+}
+
+
 const getAllRecords = async domain => {
 	let dns = {
 		NS:		[],
@@ -195,5 +247,6 @@ const getAllRecords = async domain => {
 
 module.exports = {
 	getDnsRecords,
+	getNameServers,
 	getAllRecords
 }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@layered/dns-records",
-  "version": "1.0.0",
+  "version": "1.1.0",
   "description": "Discover publicly available DNS Records for a domain",
   "keywords": [
     "dns",