Relay addresses?

Hi all,

I am setting up relay nodes, in preparation for a bit of testing. I am very new to this and still learning the ropes. I currently use the IOHK DNS for mainnet to connect to the network:

Are there other clusters, operated by IOHK or other entities, that can be used? If so, are these spread around different geographic locations (eg, one for Asia-Pacific, on for Europe, etc)? Is there a list somewhere?

I apologise in advance if this question has already been asked, please feel free to direct me elsewhere if need be.

Thank you,