Node.js dns.resolve()方法
原文:https://www.geeksforgeeks.org/node-js-dns-resolve-method/
dns.resolve()方法是 dns 模块的内置应用程序编程接口，用于将主机名解析为资源记录数组。
语法:
dns.resolve( hostname, rrtype, callback )
参数:该方法接受三个参数，如上所述，如下所述:
- 主机名:该参数指定一个字符串，该字符串表示要解析的主机名。
- rrtype: 指定资源记录类型。它的默认值是“A”。记录列表(“A”、“AAAA”、“任何”、“CNAME”、“MX”、“TXT”、“NS”、“NAPTR”、“PTR”、“SOA”、“SRV”)描述如下:
- A: IPv4 地址
- AAAA: IPv6 地址
- 任意:任意记录
- CNAME: 典名记载
- MX: 邮件交换记录
- NAPTR: 名称权限指针记录
- NS: 名称服务器记录
- PTR: 指针记录
- SOA: 权限记录的开始
- SRV: 服务记录
- TXT: 文字记录
-
callback: It specifies a function which to be called after DNS resolution of the hostname.
- 错误:如果生成，则指定错误。
- 记录:表示返回记录的字符串或对象。
返回值:这个方法通过回调函数返回错误、记录，这些数据作为参数传递给回调函数。
下面的例子说明了在 Node.js 中使用 dns.resolve()方法:
例 1:
```js // Node.js program to demonstrate the // dns.resolve() method
// Accessing dns module const dns = require('dns');
// Set the rrtype for dns.resolve() method const rrtype="A";
// Calling dns.resolve() method for hostname // geeksforgeeks.org and print them in // console as a callback dns.resolve('geeksforgeeks.org', rrtype, (err, records) => console.log('records: %j', records)); ```
输出:
js records: ["34.218.62.116"]例 2:
```js // Node.js program to demonstrate the // dns.resolve() method
// Accessing dns module const dns = require('dns');
// Set the rrtype for dns.resolve() method const rrtype="MX";
// Calling dns.resolve() method for hostname // geeksforgeeks.org and print them in // console as a callback dns.resolve('geeksforgeeks.org', rrtype, (err, records) => console.log('records: %j', records)); ```
输出:
```js records: [ {"exchange":"alt1.aspmx.l.google.com", "priority":5}, {"exchange":"alt2.aspmx.l.google.com", "priority":5}, {"exchange":"aspmx.l.google.com", "priority":1}, {"exchange":"alt3.aspmx.l.google.com", "priority":10}, {"exchange":"alt4.aspmx.l.google.com", "priority":10} ]
```
例 3:
```js // Node.js program to demonstrate the // dns.resolve() method
// Accessing dns module const dns = require('dns');
// Set the rrtype for dns.resolve() method const rrtype="TXT";
// Calling dns.resolve() method for hostname // geeksforgeeks.org and print them in // console as a callback dns.resolve('geeksforgeeks.org', rrtype, (err, records) => console.log('records: %j', records)); ```
输出:
```js records: [ ["v=spf1 include:amazonses.com include:_spf.google.com -all"], ["fob1m1abcdp777bf2ncvnjm08n"] ]
```
例 4:
```js // Node.js program to demonstrate the // dns.resolve() method
// Accessing dns module const dns = require('dns');
// Set the rrtype for dns.resolve() method const rrtype="NS";
// Calling dns.resolve() method for hostname // geeksforgeeks.org and print them in // console as a callback dns.resolve('geeksforgeeks.org', rrtype, (err, records) => console.log('records: %j', records)); ```
输出:
```js records: [ "ns-1520.awsdns-62.org", "ns-1569.awsdns-04.co.uk", "ns-245.awsdns-30.com", "ns-869.awsdns-44.net" ]
```
注意:以上程序使用
node index.js命令编译运行。参考:https://nodejs . org/API/DNS . html # DNS _ DNS _ resolve _ hostname _ rrtype _ callback
版权属于：月萌API www.moonapi.com，转载请注明出处
