DNS NsLookup using Visual C# .NET
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.
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.
Step 1: Download and install the Network Co mponent
Download Network Component from the ActiveXperts Download Site and start the installation. The installation guides you through the installation process.
Step 2: Create a new Visual C# .NET Project
Launch Microsoft Visual Studio from the Start menu. Choose 'New' from the 'File' menu and click on 'Web Site'. In the 'Web Site' dialog, select ASP .NET Web Site. Select a name for the application and a name for the solution. Also, select the directory where you want to store the project:
(Click on the picture to enlarge)
Step 3: Refer to the Network Component Library and create the objects
Now that a new project has been created, you must add a reference to the Network Component library in the project to be able to use the Network Component object. To do so, choose 'Add Reference...' from the 'Project' menu. In the 'Add Reference' dialog that pops up, select the 'COM' tab and select the 'Network Component Type Library' as shown in the following picture:
(Click on the picture to enlarge)
Click 'OK' to close the 'Add Reference' dialog.
On top of your code, type the following line to use the Network Component namespace:
using AxNetwork;
Step 4: Perform a DNS lookup
You can now use the Network Component SDK to do a DNS address lookup.
The following code shows how to create a DNS lookup utility using Microsoft Visual C# .NET:
Appendix: Full source code
using System;
using System.IO;
using AxNetwork;
namespace DnsDemo
{
///
/// Summary description for Class1.
///
class DnsDemo
{
///
/// The main entry point for the application.
///
[STAThread]
static void Main(string[] args)
{
AxNetwork.DnsServer objDnsServer = new AxNetwork.DnsServer();
AxNetwork.NwConstants objConstants = new AxNetwork.NwConstants();
string strDnsServer = "", strHost = "", strQueryResult = "";
// A license key is required to unlock this component after the trial period has expired.
// Call 'Activate' with a valid license key as its first parameter. Second parameter determines whether to save the license key permanently
// to the registry (True, so you need to call Activate only once), or not to store the key permanently (False, so you need to call Activate
// every time the component is created). For details, see manual, chapter "Product Activation".
/*
objDnsServer.Activate( "XXXXX-XXXXX-XXXXX", false );
*/
// Display component information
Console.WriteLine("ActiveXperts Network Component {0}\nBuild: {1}\nModule: {2}\nLicense Status: {3}\nLicense Key: {4}\n", objDnsServer.Version, objDnsServer.Build, objDnsServer.Module, objDnsServer.LicenseStatus, objDnsServer.LicenseKey);
// Set Logfile (optional, for debugging purposes)
objDnsServer.LogFile = Path.GetTempPath() + "Dns.log";
Console.WriteLine("Log file used: {0}\n", objDnsServer.LogFile);
strDnsServer = ReadInput( "Enter DNS server: " );
strHost = ReadInput( "Enter domain or host: " );
objDnsServer.Server = strDnsServer;
objDnsServer.Lookup( strHost, objConstants.nwDNS_TYPE_ANY );
Console.WriteLine( "Lookup, result: " + objDnsServer.LastError.ToString() + " (" + objDnsServer.GetErrorDescription(objDnsServer.LastError) + ")" );
if( objDnsServer.LastError == 0 )
{
if( objDnsServer.IsAuthoritative )
Console.WriteLine( "Server is an authority for this domain" );
else
Console.WriteLine( "Server is not an authority for this domain" );
}
Console.WriteLine( "" );
if( objDnsServer.LastError == 0 )
{
DnsRecord objDnsRecord = ( DnsRecord ) objDnsServer.GetFirstRecord ();
while( objDnsServer.LastError == 0 )
{
if ( objDnsRecord.Type == objConstants.nwDNS_TYPE_A )
{
strQueryResult += "\r\nType: A\r\n";
strQueryResult += "\r\n\tName: " + objDnsRecord.Name;
strQueryResult += "\r\n\tAddress: " + objDnsRecord.Address;
}
if ( objDnsRecord.Type == objConstants.nwDNS_TYPE_AAAA )
{
strQueryResult += "\r\nType: AAAA\r\n";
strQueryResult += "\r\n\tName: " + objDnsRecord.Name;
strQueryResult += "\r\n\tAddress: " + objDnsRecord.Address;
}
if ( objDnsRecord.Type == objConstants.nwDNS_TYPE_CNAME )
{
strQueryResult += "\r\nType: CNAME\r\n";
strQueryResult += "\r\n\tName: " + objDnsRecord.Name;
strQueryResult += "\r\n\tAlias: " + objDnsRecord.Address;
}
if ( objDnsRecord.Type == objConstants.nwDNS_TYPE_NS )
{
strQueryResult += "\r\nType: NS\r\n";
strQueryResult += "\r\n\tName: " + objDnsRecord.Name;
strQueryResult += "\r\n\tNameServer: " + objDnsRecord.NameServer;
}
if ( objDnsRecord.Type == objConstants.nwDNS_TYPE_MX )
{
strQueryResult += "\r\nType: MX\r\n";
strQueryResult += "\r\n\tName: " + objDnsRecord.Name;
strQueryResult += "\r\n\tPreference: " + objDnsRecord.Preference;
strQueryResult += "\r\n\tMailExchange: " + objDnsRecord.MailExchange;
}
if ( objDnsRecord.Type == objConstants.nwDNS_TYPE_PTR )
{
strQueryResult += "\r\nType: PTR\r\n";
strQueryResult += "\r\n\tName: " + objDnsRecord.Name;
strQueryResult += "\r\n\tAddress: " + objDnsRecord.Address;
}
if ( objDnsRecord.Type == objConstants.nwDNS_TYPE_SOA )
{
strQueryResult += "\r\nType: SOA\r\n";
strQueryResult += "\r\n\tName: " + objDnsRecord.Name;
strQueryResult += "\r\n\tName Server: " + objDnsRecord.NameServer;
strQueryResult += "\r\n\tMailBox: " + objDnsRecord.MailBox;
strQueryResult += "\r\n\tSerial: " + objDnsRecord.SerialNumber;
strQueryResult += "\r\n\tRefresh: " + objDnsRecord.RefreshInterval;
strQueryResult += "\r\n\tRetry Interval: " + objDnsRecord.RetryInterval;
strQueryResult += "\r\n\tExpiration Limit: " + objDnsRecord.ExpirationLimit;
strQueryResult += "\r\n\tMinimum TTL: " + objDnsRecord.MinimumTTL;
}
objDnsRecord = ( DnsRecord ) objDnsServer.GetNextRecord ();
}
}
Console.WriteLine( strQueryResult );
Console.WriteLine( "Ready." );
System.Threading.Thread.Sleep(5000); // Sleep for 5 seconds before exit
}
static private string ReadInput( string strTitle )
{
string strInput = "";
Console.WriteLine( strTitle );
while( strInput == "" )
{
Console.Write(" > ");
strInput = Console.ReadLine();
}
return strInput;
}
}
}
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.