ASP.NET Active Directory Auto-Login

Question

I'm making a simple website to learn about asp.net/AD authentication.

I used some of the code snippets from this tutorial: https://support.microsoft.com/en-us/kb/316748 to successfully use AD with Forms Authentication from a login page. I use these IIS Authentication settings for the website:

Anonymous Authentication    -Enabled
ASP.NET Impersonation       -Disabled
Basic Authentication        -Disabled
Digest Authentication       -Disabled
Forms Authentication        -Enabled
Windows Authentication      -Disabled

I want to use the credentials for the currently logged in windows user and either not prompt or only prompt if it fails. When I change the Web.config authentication mode to "Windows" and the the IIS settings as shown below it has a pop-up credentials prompt but just keeps prompting and never accepts the credentials.

Anonymous Authentication    -Enabled
ASP.NET Impersonation       -Disabled
Basic Authentication        -Disabled
Digest Authentication       -Disabled
Forms Authentication        -Disabled
Windows Authentication      -Enabled

I've tried several other combinations but they all failed.

All files in this website are:

LdapAuthentication.cs - is in App_Code and is a direct copy/paste from the tutorial
Logon.aspx - is copy/pasted from the tutorial with the companies LDAP path added
Default.aspx - is a direct copy/paste from the WebForm1.aspx in the tutorial
Web.config (shown below)

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.5">
      <assemblies>
        <add assembly="System.DirectoryServices, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
      </assemblies>
    </compilation>
    <httpRuntime targetFramework="4.5" />
    <authentication mode="Forms"> <!-- I also tried "Windows" -->
      <forms loginUrl="logon.aspx" name="adAuthCookie" timeout="10" path="/" />
    </authentication>
    <authorization>
      <deny users="?" />
      <allow users="*" />
    </authorization>
    <identity impersonate="true" />
    <anonymousIdentification enabled="false" />
  </system.web>
  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />
  </system.webServer>
</configuration>

Answer 1

Ensure that IIS is right configured to use ActiveDirectory Authentication with Forms, it works with local server from Visual studio but not in IIS. In IIS 7+ it's the application pool account. - Simply create a new application pool that runs under that account and assign that app pool to your application/site. - Right click to the new pool (example ASP.NET V4.0 Mypool) - > Advanced Settings - In Process model, choose LocalSystem as Identity. Web.config:

<system.web>
<compilation targetFramework="4.0" debug="true"/>
..........
<authentication mode="Forms">
      <forms loginUrl="login.aspx" name="adAuthCookie" timeout="10" path="/"/>
    </authentication>    
    <identity impersonate="false"/>
    <authorization>
      <deny users="?"/>
      <allow users="*"/>
    </authorization>
</system.web>