How to create a dns resolver in c# ✅ [ No hide tags ]

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Today you will learn how to create a c# dns resolver.

Step 1: Create a new Console Application Project

Open up Visual Studio and create a new Console Application project. You can name the project whatever you like.

Step 2: Import the necessary namespaces

In order to use the Dns and Uri classes, we need to import the System.Net namespace. We can do this by adding the following line of code at the top of our Program.cs file:

Code:

using System.Net;

Step 3: Prompt the user to input a domain name

We want to prompt the user to input a domain name. We can do this by adding the following code to the Main method:

Code:

Console.Write("Enter a domain name: ");
string domain = Console.ReadLine();

This will display the message "Enter a domain name: " in the console and wait for the user to input a domain name.

Step 4: Check if the entered domain name is valid

Before we attempt to get the DNS information for the entered domain, we want to make sure that the domain name is valid. We can use the Uri.CheckHostName() method to do this. We can add the following code after prompting the user for input:

Code:

if (Uri.CheckHostName(domain) == UriHostNameType.Unknown)
{
Console.WriteLine($"Invalid domain name: {domain}");
return;
}

If the Uri.CheckHostName() method returns UriHostNameType.Unknown, it means that the entered domain name is not a valid domain. We print an error message and return from the function.

Step 5: Get the DNS information for the domain

Assuming the entered domain name is valid, we can now attempt to get the DNS information for the domain. We can use the Dns.GetHostEntry() method to do this. We can add the following code after checking if the entered domain name is valid:

Code:

try
{
IPHostEntry hostEntry = Dns.GetHostEntry(domain);

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Console.WriteLine($"DNS information for {domain}:");
foreach (IPAddress ipAddress in hostEntry.AddressList)
{
Console.WriteLine(ipAddress);
}
}
catch (Exception e)
{
Console.WriteLine($"Error getting DNS information for {domain}: {e.Message}");
}

We wrap the call to Dns.GetHostEntry() in a try-catch block in case an exception occurs while attempting to get the DNS information. If the DNS information is successfully retrieved, we print out the IP addresses associated with the domain.

If an error occurs while getting the DNS information, we print an error message containing the domain name and the exception message.

Step 6: Run the program

We can now run the program and test it out. When we run the program, we should see the message "Enter a domain name: " in the console. We can enter a domain name and press enter to see the DNS information for the domain, or an error message if the entered domain name is invalid or an error occurs while getting the DNS information.