i also forgot another feature, it has a replication protocol so you can run several relays, you set them up with a secret relay key and then use the pubkey of the other relays in the cluster, and every event that goes into one gets pushed to all the others. this is to enable a high availability or multi-location relay network, how you set that part up is however you want. a multi-IP address DNS can be used or you can just have them on like regional relay subdomains but have them all linked together as one database.
very basic but it would be especially good for reliability and censorship resistance (eg, putting several relays up in several diverse jurisdictions)