DNS NsLookup using Visual C++

Network Component provides an easy-to-use development interface to a variety of IP protocols. By using Network Component, you can very easily create or enhance applications with network features.

Network Component features the following: DNS, FTP, HTTP, HTTPs, ICMP Ping, IP-to-Country, MSN, NTP, RSH, SCP, SFTP, SNMP v1/v2c (Get, GetNext, Set), SNMP Traps, SNMP MIB, SSH, TCP, Telnet, TFTP, UDP, Telnet, Wake-On-LAN and more.

Network Component can be well integrated into any development platform that supports ActiveX objects.

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The Domain Name System (DNS) is the method by which Internet addresses in mnemonic form - such as www.activexperts.com - are converted into the equivalent numeric IP address such as 212.97.55.136. To the user and application process this translation is a service provided either by the local host or from a remote host via the Internet. The DNS server (or resolver) may communicate with other Internet DNS servers if it cannot translate the address itself. DNS names are constructed hierarchically. The highest level of the hierarchy is the last component or label of the DNS address. Labels can be up to 63 characters long and are not case sensitive. A maximum length of 255 characters is allowed. Labels must start with a letter and can only consist of letters, digits and hyphens.

Nslookup is a popular program for UNIX, Linux and Windows to query Internet domain name servers. It allows the user to query name servers for information about various hosts and domains or to print a list of hosts in a domain.

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Step 1: Create a new Visual C++ project

Launch 'Microsoft Visual C++' from the Start menu, and choose 'New' from the 'File Menu'. The 'New' dialog appears.

Select the type of project (for instance: 'Win32 Console Application'), enter a 'Project name' and select the 'Location':

Select the kind of project, for instance a 'Hello, world!' application and click 'Finish':

Step 2: Refer to the Network Component Library and declare the objects

A new Project is created now.

Before you can use Network Component, you need to refer to the Network Component library. The actually reference files are shipped with the product and are located in the following directory:

C:\Program Files\ActiveXperts\Network Component\Examples\Visual C++\Include

Copy all files in the above directory ('AxNetwork.c', 'AxNetwork_i.c' and 'AxNetworkConstants.h') to your project directory.

On top of your code, declare the following object:

IDnsServer  *pDnsServer = NULL;

Step 3: Create the objects

Since the Network Component is a COM object, you must initialize the COM library before they can call COM library functions (e.g. Network Component functions):

CoInitialize(NULL);

Create the object in the following way:

CoCreateInstance(CLSID_DnsServer,NULL,CLSCTX_INPROC_SERVER,IID_IDnsServer, (void**) &pDnsServer);

Appendix: Full source code

// Demo.cpp : Defines the entry point for the console application.
//

#include <windows.h>
#include <stdio.h>
#include <comdef.h>
#include <atlbase.h>

#include "..\..\include\AxNetworkConstants.h"
#include "..\..\include\AxNetwork.h"
#include "..\..\include\AxNetwork_i.c"

LPTSTR ReadInput( LPCTSTR lpszTitle, BOOL bAllowEmpty = FALSE );
LPTSTR GetErrorDescription( LONG lLastError, IIcmp *pIcmp );


int main()
{
  IIcmp        *pIcmp    = NULL;
  HRESULT        hr;
  LONG        lLastError  = -1L;
  LONG        lLastDuration = -1L, lLastTtl = -1L;
  LPTSTR        lptszHost  = NULL;
  int          i;

  // Initialize COM  
  CoInitialize(NULL);

  // Create objects
  hr = CoCreateInstance(CLSID_Icmp, NULL, CLSCTX_INPROC_SERVER, IID_IIcmp, (void**) &pIcmp);
  if( ! SUCCEEDED( hr ) )
  {
    _tprintf( _T("Unable to create Icmp object.\n") );
    goto _EndMain;
  }

  lptszHost = ReadInput( _T("Enter host: ") );
  pIcmp->put_Ttl( 255 );
  for( i = 0; i < 4; i++ )
  {
    pIcmp->Ping( _bstr_t( lptszHost ), 5000 );  // 5000: timeout in msecs
    pIcmp->get_LastError( &lLastError );
    if( lLastError != 0 )
    {
      _tprintf( _T("Ping, result: %ld (%s)\n"), lLastError, GetErrorDescription( lLastError, pIcmp ) );
    }
    else
    {
      pIcmp->get_LastDuration( &lLastDuration );
      pIcmp->get_LastTtl( &lLastTtl );
      _tprintf( _T("Reply from %s; time=%ld TTL=%ld\n"), lptszHost, lLastDuration, lLastTtl );
    }
    Sleep( 1000 );      
  }

  _tprintf( _T("\n") );

_EndMain:

  if( pIcmp != NULL ) 
    pIcmp->Release();

  CoUninitialize();

  _tprintf( _T("Ready.\n") );

  return 0;
}



///////////////////////////////////////////////////////////////////////////////////////////

LPTSTR GetErrorDescription( LONG lLastError, IIcmp *pIcmp )
{
  static TCHAR  tszErrorDescription[ 1024 + 1 ] = { _T('\0') };
  BSTR      bstrErrDescr = NULL;

  pIcmp->GetErrorDescription( lLastError, &bstrErrDescr );
  if( bstrErrDescr != NULL )
  {
    _stprintf_s( tszErrorDescription, 1024, _T("%ls"), bstrErrDescr );
    SysFreeString ( bstrErrDescr );

  }
  return tszErrorDescription;
}



///////////////////////////////////////////////////////////////////////////////////////////

LPTSTR ReadInput( LPCTSTR lptszTitle, BOOL bAllowEmpty )
{
  static TCHAR    tszInput [ 255 + 1 ] = { _T('\0') };

  _tprintf( _T("%s:\n"), lptszTitle );
  do
  {
    _tprintf ( _T("   > ") );
    fflush(stdin); 
    fflush(stdout); 
    _fgetts( tszInput, 255, stdin );
    if( tszInput[ 0 ] != _T('\0') && tszInput[ _tcsclen( tszInput ) - 1  ] == _T('\n') )
      tszInput[ _tcsclen( tszInput ) - 1  ] = _T('\0');
  } while( _tcsclen ( tszInput ) == 0 && ! bAllowEmpty );

  return tszInput;
}

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You can download the complete samples here. There are many other working Network Component scripts on our site and shipped with the product.

NOTE: Demo Projects are created with Microsoft Visual Studio 2008

The Network Component project ships with a set of Microsoft Visual Studio .NET samples, including samples for Microsoft Visual C# .NET. The projects are created with Microsoft Visual Studio 2008.

Users with a later version of Microsoft Visual Studio can open such a project. The Visual Studio Conversion Wizard will guide you through the process of converting the project to the version used.