Exchange Latest CU Update and DkimSigner

Hello,

I was going through the exchange servers to see what version we were on and need to do a CU upgrade. I'm new to this organization but they mentioned that we had to be careful because of the DKIMSigner would need to be ran again. Does anyone know the process of this with this DKIM signer? 

I've done plenty of CU upgrades and never dealt with this. Please let me know