Node.js dns.resolveCname()方法

原文:https://www . geesforgeks . org/node-js-DNS-resolve cname-method/

dns.resolveCname()方法是 dns 模块的内置应用程序编程接口，用于使用 dns 协议解析指定主机名的 Cname 记录。

语法:

dns.resolveCname( hostname, callback )

参数:该方法有两个参数，如上所述，如下所述:

  • Hostname: This parameter specifies a string that represents the hostname to be resolved.
  • Callback: Specifies the function to be called after DNS resolution of the host name.
    • Error: The specified generation error.
    • Address: It is a string array that represents the returned cname address of the host name.

返回值:这个方法通过回调函数返回错误、地址，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.resolveCname()方法:

例 1:

// Node.js program to demonstrate the   
// dns.resolveAny() method

// Accessing dns module
const dns = require('dns');

// Calling dns.resolveCname() method for hostname
// geeksforgeeks.org and displaying them in
// console as a callback
dns.resolveCname('geeksforgeeks.org', (err, 
    addresses) => console.log('addresses: %j', addresses));

输出:

QueryReqWrap {
  bindingName: 'queryCname',
  callback: [Function],
  hostname: 'geeksforgeeks.org',
  oncomplete: [Function: onresolve],
  ttl: false,
  channel: ChannelWrap {} }
addresses: undefined

例 2:

// Node.js program to demonstrate the   
// dns.resolveAny() method

// Accessing dns module
const dns = require('dns');

// Calling dns.resolveCname() method for hostname
// geeksforgeeks.org and displaying them in
// console as a callback
dns.resolveCname('localhost', (err, 
    addresses) => console.log('addresses: %j', addresses));

输出:

QueryReqWrap {
  bindingName: 'queryCname',
  callback: [Function],
  hostname: 'localhost',
  oncomplete: [Function: onresolve],
  ttl: false,
  channel: ChannelWrap {} }
addresses: undefined

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 _ resolvecname _ hostname _ callback

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