The ability to probe and manipulate electrons in real time constitutes one of the main challenges of transport in quantum dots. One paradigmic experiment in the topic of high frequency is the quantum RC circuit, its behavior being governed by the interplay between quantum coherence and interaction effects.This circuit is the quantum analogue of the classical RC circuit: it comprises a dot capacitively coupled to a nearby gate and connected to a single reservoir lead. In this talk, I will discuss the emergence of universal and quantized expressions for the AC resistance of this circuit, and derive an effective low energy model for this problem. In the case of the Anderson model, I will show that a giant peak develops in the AC resistance as the magnetic field is varied.