Programmatically obtain user information from Active Directory

Here is a sample method that you can use for contacting Active Directory in order to obtain information about a user based on his/her username/account name (a.k.a. sAMAccountName in AD):

public void GetUserDistinguishedName(string sAMAccountName)
{
    using (DirectoryEntry dirEntry = new DirectoryEntry())
    {
        dirEntry.Path = "LDAP://OU=OUName,DC=DCName,DC=org";
        dirEntry.AuthenticationType = AuthenticationTypes.Secure;

        using (DirectorySearcher dirSearch = new DirectorySearcher(dirEntry))
        {
            dirSearch.Filter = string.Format("(&(objectCategory=person)(objectClass=user)(SAMAccountName={0}))", sAMAccountName);
            SearchResult result = dirSearch.FindOne();
            if (result != null)
            {
                Console.WriteLine(string.Format("Distinguished Name: {0}" ,result.Properties["distinguishedname"][0].ToString()));
                Console.WriteLine(string.Format("First Name: {0}", result.Properties["givenname"][0].ToString()));
                Console.WriteLine(string.Format("Last Name: {0}", result.Properties["sn"][0].ToString()));
                Console.WriteLine(string.Format("Email Address: {0}", result.Properties["mail"][0].ToString()));
            }
        }
    }
}