Private Sub AddDivMessage()
    Dim CurrentUri As New Uri(WebBrowser1.Url.ToString())
    Dim HostName As String

    ' Ensure we have a host name, and not just an IP, against which to test.
    If (Not CurrentUri.HostNameType = UriHostNameType.Dns) Then
        Dim Permit As New DnsPermission(System.Security.Permissions.PermissionState.Unrestricted)
        Permit.Assert()

        Dim HostEntry As IPHostEntry = System.Net.Dns.GetHostEntry(CurrentUri.Host)
        HostName = HostEntry.HostName
    Else
        HostName = CurrentUri.Host
    End If

    If (Not HostName.Contains("adatum.com")) Then
        AddTopPageMessage("You are viewing a web site other than ADatum.com. " & _
            "Please exercise caution, and ensure your web surfing complies with all " & _
            "corporate regulations as laid out in the company handbook.")
    End If
End Sub

Private Sub AddTopPageMessage(ByVal Message As String)
    If (WebBrowser1.Document IsNot Nothing) Then
        With WebBrowser1.Document
            ' Do not insert the warning again if it already exists. 
            Dim ReturnedElems As HtmlElementCollection = .All.GetElementsByName("ADatumWarningDiv")
            If (Not (ReturnedElems Is Nothing) And (ReturnedElems.Count > 0)) Then
                Exit Sub
            End If

            Dim DivElem As HtmlElement = .CreateElement("DIV")
            DivElem.Name = "ADatumWarningDiv"
            DivElem.Style = "background-color:black;color:white;font-weight:bold;width:100%;"
            DivElem.InnerText = Message

            DivElem = .Body.InsertAdjacentElement(HtmlElementInsertionOrientation.AfterBegin, DivElem)
        End With
    End If
End Sub

        public void AddDivMessage()
        {
            Uri currentUri = new Uri(webBrowser1.Url.ToString());
            String hostName = null;

            // Ensure we have a host name, and not just an IP, against which to test.
            if (!(currentUri.HostNameType == UriHostNameType.Dns))
            {
                DnsPermission permit = new DnsPermission(System.Security.Permissions.PermissionState.Unrestricted);
                permit.Assert();

                IPHostEntry hostEntry = System.Net.Dns.GetHostEntry(currentUri.Host);
                hostName = hostEntry.HostName;
            } else {
                hostName = currentUri.Host;
            }

            if (!hostName.Contains("adatum.com"))
            {
                AddTopPageMessage("You are viewing a web site other than ADatum.com. " +
                    "Please exercise caution, and ensure your Web surfing complies with all " +
                    "corporate regulations as laid out in the company handbook.");
            }
        }

        private void AddTopPageMessage(String message)
        {
            if (webBrowser1.Document != null) 
            {
                HtmlDocument doc = webBrowser1.Document;

                // Do not insert the warning again if it already exists. 
                HtmlElementCollection returnedElems = doc.All.GetElementsByName("ADatumWarningDiv");
                if ((returnedElems != null) && (returnedElems.Count > 0)) 
                {
                    return;
                }

                HtmlElement divElem = doc.CreateElement("DIV");
                divElem.Name = "ADatumWarningDiv";
                divElem.Style = "background-color:black;color:white;font-weight:bold;width:100%;";
                divElem.InnerText = message;

                divElem = doc.Body.InsertAdjacentElement(HtmlElementInsertionOrientation.AfterBegin, divElem);
            }
        }