ldap authentication using ActiveDirectyoryMembershipProvider on GC port fails in MVC2 application - asp.net-mvc-2

Question

I am developing an MVC2 application using C# ASP.NET.
In my application I am using ActiveDirectoryMembershipProvider for user authentication. Below is the snippet from my web.config file.
If I use the global catalog port 3268 in my connection string I get the error "LDAP connections on GC port are not supported against Active Directory". I did google on this error message and was unable to find an appropriate solution. Many people have suggested using port 389, some have suggested code changes. But I want to be able to use the GC port to allow users connected to different forests, because it is more cleaner.
Some observations:
The same connection string(with port 3268) is working perfectly for other applications in my company i.
When I change my connection string to point to port 389 it works perfectly i.e people who belong to the local domain are able to log in. However people from another domain cant.
I put breakpoints in my AcconuntModel and AccountController. With connection string pointing to port 3268,Membership.Provider threw "ConfigurationErrorsException".
It would be very helpful if someone can help me resolve this issue.
web.config:
<add name="ADConnectionString" connectionString="LDAP://myADServer.abc.ad:389/DC=abc,DC=ad" />
<membership defaultProvider="MyADMembershipProvider">
<providers>
<clear />
<add connectionStringName="ADConnectionString" maxInvalidPasswordAttempts="1000" connectionUsername="ldapuser#abc.ad" connectionPassword="password" connectionProtection="None" enableSearchMethods="True" name="MyADMembershipProvider" type="System.Web.Security.ActiveDirectoryMembershipProvider,System.Web, Version=2.0.0.0,Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
<add name="MySqlMembershipProvider" type="MySql.Web.Security.MySQLMembershipProvider,MySql.Web,Version=6.5.4.0,Culture=neutral,PublicKeyToken=c5687fc88969c44d" connectionStringName="MySqlMembershipConnection" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="true" passwordFormat="Hashed" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10" applicationName="/" autogenerateschema="true" />
</providers>
</membership>
<!-- Added for custom provider -->
<roleManager enabled="true" cacheRolesInCookie="true" defaultProvider="DDMS_Custom_RoleProvider">
<providers>
<clear />
<add applicationName="/" connectionStringName="ddms_dataEntities2" name="DDMS_Custom_RoleProvider" type="DDMS_sourcecode.Utilities.DDMS_Custom_RoleProvider, DDMS_sourcecode" />
<add connectionStringName="ApplicationServices" applicationName="/" autogenerateschema="true" name="MySqlRoleProvider" type="MySql.Web.Security.MySQLRoleProvider,MySql.Web,Version=6.5.4.0,Culture=neutral,PublicKeyToken=c5687fc88969c44d" />
</providers>
</roleManager>

Answer 1

If it is Global Catalog that you need to search, why dont you try it this way
using (DirectoryEntry searchRoot = new DirectoryEntry("GC://DC=yourdomain,DC=com"))
using (DirectorySearcher ds = new DirectorySearcher(searchRoot))
{
ds.Filter = "(sAMAccountName=userID1)";
ds.SearchScope = SearchScope.Subtree;
using (SearchResultCollection src = ds.FindAll())
{
foreach (SearchResult sr in src)
{
uxFred.Content = sr.Path;
}
}
}