By the title of this post, you can probably tell how much I know about CA’s in AD. About a month ago, while installing an Exchange 2007 server into the organization, I removed the Certificate Authority service unintentionally. I think that’s what must have happened anyway. We have third party certificates that we use for our SSL stuff, so I didn’t think it was necessary. I’ve noticed that since I did this, I’ve been getting these KDC event 20’s about once or twice a day. I re-installed the CA service, but I still get the events. I read a post somewhere to install the Enterprise PKI mmc. I can see that the originally issued CA has its AIA, CRL and CDP location status as “unable to download”. How do I clean this up without breaking anything that might be dependent on this service?