For my domain (https://www.poof.io https://www.poof.io), it's www. If you just use something like https://poof.io https://poof.io, then it would be @. Depends

For my domain (https://www.poof.io https://www.poof.io), it's www. If you just use something like https://poof.io https://poof.io, then it would be @. Depends on your site. There should be a few historical IP addresses, but you would create an A record for each of them.