No violation of any of the provisions of this part relating to real estate or of Chapter 1 (commencing with Section 11000) of Part 2 of this division by any real estate salesperson or employee of any licensed real estate broker shall cause the revocation or suspension of the license of the responsible broker retaining the salesperson or the broker employing the employee unless it appears upon a hearing by the commissioner that the responsible broker or broker had guilty knowledge of the violation.