Updated

EonaCat.DnsTester/MainForm.Designer.cs

@@ -49,6 +49,12 @@
             this.StatusBox = new System.Windows.Forms.ListBox();
             this.chkDns1 = new System.Windows.Forms.CheckBox();
             this.chkDns2 = new System.Windows.Forms.CheckBox();
+            this.label1 = new System.Windows.Forms.Label();
+            this.label2 = new System.Windows.Forms.Label();
+            this.txtResolveIP = new System.Windows.Forms.TextBox();
+            this.txtResolveHost = new System.Windows.Forms.TextBox();
+            this.btnResolveIP = new System.Windows.Forms.Button();
+            this.btnResolveHost = new System.Windows.Forms.Button();
             this.SuspendLayout();
             // 
             // ResultView
@@ -231,7 +237,7 @@
             this.chkDns1.AutoSize = true;
             this.chkDns1.Checked = true;
             this.chkDns1.CheckState = System.Windows.Forms.CheckState.Checked;
-            this.chkDns1.Location = new System.Drawing.Point(277, 205);
+            this.chkDns1.Location = new System.Drawing.Point(277, 220);
             this.chkDns1.Name = "chkDns1";
             this.chkDns1.Size = new System.Drawing.Size(245, 36);
             this.chkDns1.TabIndex = 24;
@@ -243,13 +249,65 @@
             this.chkDns2.AutoSize = true;
             this.chkDns2.Checked = true;
             this.chkDns2.CheckState = System.Windows.Forms.CheckState.Checked;
-            this.chkDns2.Location = new System.Drawing.Point(1229, 205);
+            this.chkDns2.Location = new System.Drawing.Point(1229, 220);
             this.chkDns2.Name = "chkDns2";
             this.chkDns2.Size = new System.Drawing.Size(245, 36);
             this.chkDns2.TabIndex = 25;
             this.chkDns2.Text = "Test dns server";
             this.chkDns2.UseVisualStyleBackColor = true;
             // 
+            // label1
+            // 
+            this.label1.AutoSize = true;
+            this.label1.Location = new System.Drawing.Point(155, 27);
+            this.label1.Name = "label1";
+            this.label1.Size = new System.Drawing.Size(263, 32);
+            this.label1.TabIndex = 26;
+            this.label1.Text = "Resolve ip address:";
+            // 
+            // label2
+            // 
+            this.label2.AutoSize = true;
+            this.label2.Location = new System.Drawing.Point(1102, 27);
+            this.label2.Name = "label2";
+            this.label2.Size = new System.Drawing.Size(257, 32);
+            this.label2.TabIndex = 27;
+            this.label2.Text = "Resolve hostname:";
+            // 
+            // txtResolveIP
+            // 
+            this.txtResolveIP.Location = new System.Drawing.Point(425, 21);
+            this.txtResolveIP.Name = "txtResolveIP";
+            this.txtResolveIP.Size = new System.Drawing.Size(608, 38);
+            this.txtResolveIP.TabIndex = 28;
+            // 
+            // txtResolveHost
+            // 
+            this.txtResolveHost.Location = new System.Drawing.Point(1365, 21);
+            this.txtResolveHost.Name = "txtResolveHost";
+            this.txtResolveHost.Size = new System.Drawing.Size(651, 38);
+            this.txtResolveHost.TabIndex = 29;
+            // 
+            // btnResolveIP
+            // 
+            this.btnResolveIP.Location = new System.Drawing.Point(425, 75);
+            this.btnResolveIP.Name = "btnResolveIP";
+            this.btnResolveIP.Size = new System.Drawing.Size(195, 70);
+            this.btnResolveIP.TabIndex = 30;
+            this.btnResolveIP.Text = "Resolve";
+            this.btnResolveIP.UseVisualStyleBackColor = true;
+            this.btnResolveIP.Click += new System.EventHandler(this.btnResolveIP_Click);
+            // 
+            // btnResolveHost
+            // 
+            this.btnResolveHost.Location = new System.Drawing.Point(1366, 75);
+            this.btnResolveHost.Name = "btnResolveHost";
+            this.btnResolveHost.Size = new System.Drawing.Size(221, 70);
+            this.btnResolveHost.TabIndex = 31;
+            this.btnResolveHost.Text = "Resolve";
+            this.btnResolveHost.UseVisualStyleBackColor = true;
+            this.btnResolveHost.Click += new System.EventHandler(this.btnResolveHost_Click);
+            // 
             // MainForm
             // 
             this.AutoScaleDimensions = new System.Drawing.SizeF(240F, 240F);
@@ -257,6 +315,12 @@
             this.AutoSize = true;
             this.AutoSizeMode = System.Windows.Forms.AutoSizeMode.GrowAndShrink;
             this.ClientSize = new System.Drawing.Size(2517, 1693);
+            this.Controls.Add(this.btnResolveHost);
+            this.Controls.Add(this.btnResolveIP);
+            this.Controls.Add(this.txtResolveHost);
+            this.Controls.Add(this.txtResolveIP);
+            this.Controls.Add(this.label2);
+            this.Controls.Add(this.label1);
             this.Controls.Add(this.chkDns2);
             this.Controls.Add(this.chkDns1);
             this.Controls.Add(this.StatusBox);
@@ -306,6 +370,12 @@
         private System.Windows.Forms.ListBox StatusBox;
         private System.Windows.Forms.CheckBox chkDns1;
         private System.Windows.Forms.CheckBox chkDns2;
+        private System.Windows.Forms.Label label1;
+        private System.Windows.Forms.Label label2;
+        private System.Windows.Forms.TextBox txtResolveIP;
+        private System.Windows.Forms.TextBox txtResolveHost;
+        private System.Windows.Forms.Button btnResolveIP;
+        private System.Windows.Forms.Button btnResolveHost;
     }
 }
 

EonaCat.DnsTester/MainForm.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Data;
 using System.IO;
+using System.Linq;
 using System.Net;
 using System.Net.Sockets;
 using System.Security.Cryptography;
@@ -8,6 +9,7 @@ using System.Text;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using System.Windows.Forms;
+using System.Windows.Threading;
 
 namespace EonaCat.DnsTester
 {
@@ -405,7 +407,64 @@ namespace EonaCat.DnsTester
 
 		}
 
-		private void StatusBoxPrint(string LogText)
+        private async void btnResolveIP_Click(object sender, EventArgs e)
+        {
+			if (string.IsNullOrWhiteSpace(txtResolveIP.Text))
+			{
+				MessageBox.Show("Please enter an IP address to resolve");
+				return;
+			}
+
+			if (!IPAddress.TryParse(txtResolveIP.Text , out IPAddress iPAddress))
+			{
+				MessageBox.Show("Please enter a valid IP address");
+				return;
+            }
+
+			try
+			{
+				await Task.Run(() =>
+				{
+					var dnsEntry = Dns.GetHostEntry(iPAddress);
+					Dispatcher.CurrentDispatcher.Invoke(() =>
+					{
+						txtResolveHost.Text = dnsEntry.HostName;
+					});
+                });
+			}
+			catch (Exception)
+			{
+				MessageBox.Show($"Could not get hostname for IP address '{txtResolveIP.Text}'");
+			}
+        }
+
+        private async void btnResolveHost_Click(object sender, EventArgs e)
+        {
+            if (string.IsNullOrWhiteSpace(txtResolveHost.Text))
+            {
+                MessageBox.Show("Please enter an hostname to resolve");
+                return;
+            }
+
+            try
+            {
+				await Task.Run(() =>
+				{
+					var dnsEntry = Dns.GetHostEntry(txtResolveHost.Text);
+
+					Dispatcher.CurrentDispatcher.Invoke(() =>
+					{
+						txtResolveIP.Text = dnsEntry.AddressList.Where(x => x.AddressFamily == AddressFamily.InterNetwork).FirstOrDefault().Address.ToString();
+					});
+				});
+            }
+            catch (Exception)
+            {
+                MessageBox.Show($"Could not get hostname for IP address '{txtResolveIP.Text}'");
+            }
+        }
+
+        private void StatusBoxPrint(string LogText)
 		{
 			StatusBox.Items.Add(DateTime.Now + "  " + LogText);
 			StatusBox.TopIndex = StatusBox.Items.Count - 1;