C# program to Display Hostname and IP address

To find the hostname of the current machine, use the Dns.GetHostName() method in C#. This method returns the host name of the local computer as a string. To get the IP addresses, use the IPHostEntry.AddressList property which provides an array of all IP addresses associated with the hostname.

Syntax

Following is the syntax for getting the hostname −

string hostName = Dns.GetHostName();

Following is the syntax for getting IP addresses −

IPHostEntry hostEntry = Dns.GetHostEntry(hostName);
IPAddress[] addresses = hostEntry.AddressList;

Example

The following code demonstrates how to display hostname and IP addresses −

using System;
using System.Net;

class Program {
   static void Main() {
      String hostName = string.Empty;
      hostName = Dns.GetHostName();
      Console.WriteLine("Hostname: " + hostName);
      
      IPHostEntry myIP = Dns.GetHostEntry(hostName);
      IPAddress[] address = myIP.AddressList;
      
      for (int i = 0; i < address.Length; i++) {
         Console.WriteLine("IP Address {0}: {1}", i + 1, address[i].ToString());
      }
   }
}

The output of the above code is −

Hostname: DESKTOP-ABC123
IP Address 1: 192.168.1.100
IP Address 2: ::1
IP Address 3: 127.0.0.1

Using GetHostEntry with Different Parameters

You can also get host information using an IP address or a specific hostname −

using System;
using System.Net;

class Program {
   static void Main() {
      try {
         // Get host info by IP address
         IPHostEntry hostInfo = Dns.GetHostEntry("127.0.0.1");
         Console.WriteLine("Host name for 127.0.0.1: " + hostInfo.HostName);
         
         // Get host info by domain name
         IPHostEntry googleInfo = Dns.GetHostEntry("google.com");
         Console.WriteLine("IP addresses for google.com:");
         
         foreach (IPAddress ip in googleInfo.AddressList) {
            Console.WriteLine(ip.ToString());
         }
      } catch (Exception ex) {
         Console.WriteLine("Error: " + ex.Message);
      }
   }
}

The output of the above code is −

Host name for 127.0.0.1: localhost
IP addresses for google.com:
142.250.191.46
2607:f8b0:4004:c1b::65
2607:f8b0:4004:c1b::71
2607:f8b0:4004:c1b::8a
2607:f8b0:4004:c1b::66

Key Points

• Dns.GetHostName() returns the hostname of the local machine.

• Dns.GetHostEntry() can accept a hostname or IP address as parameter.

• The AddressList property contains both IPv4 and IPv6 addresses.

• Always use try-catch blocks when working with DNS operations as they can throw exceptions.

Conclusion

The Dns class in C# provides methods to retrieve hostname and IP address information. Use GetHostName() for the local machine's hostname and GetHostEntry() to resolve hostnames to IP addresses or vice versa.