Check UserID exists in Active Directory using C#

Question

How can we check whether the USERID exists in Active Directory or not.

I have LDAP String and UserID, can I find whether that UserID exists in Active Directory or no

Answer 1

I would use the System.DirectoryServices.AccountManagement namespace.

string UserID = "grhm";
bool userExists = false;

using (var ctx = new PrincipalContext(ContextType.Domain))
{
    using (var user = UserPrincipal.FindByIdentity(ctx, UserID))
    {
        if (user != null)
        {
            userExists = true;
            user.Dispose();
        }
    }
}

See http://msdn.microsoft.com/en-us/library/bb344891.aspx for more info