How to Use ACME DNS Challenge in Amazon Route 53 to Get a Free SSL Certificate

When using UnoSSL to issue a free SSL certificate for my website, it asked me to verify my ownership of the domain first.

While when adding the second TXT record, I met below issue, saying “A record with the specified name already exists”:

Actually this turned out to be a very silly question, as I missed Route 53’s hint when creating the very first ACME challenge record. It has already told me that I should put multiple values on separate lines.

After fixing this, I got the ,one and only one, record created successfully.

Finally I passed the verification on UnoSSL and got my free SSL certificate issued.