Cannot generate new certificates | Invalid response /.well-known/acme-challenge/XXX | Challenge failed for domain

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I was able to generate the certificates for earnanswers.com. Thank you!

Now, when trying to generate the certificates for subdomain second, when executing this:

sudo certbot -v --nginx -d second.earnanswers.com -d www.second.earnan
swers.com

The output:

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator nginx, Installer nginx
Requesting a certificate for second.earnanswers.com and www.second.earnanswers.com
Performing the following challenges:
http-01 challenge for www.second.earnanswers.com
Waiting for verification...
Challenge failed for domain www.second.earnanswers.com
http-01 challenge for www.second.earnanswers.com

Certbot failed to authenticate some domains (authenticator: nginx). The Certificate Authority reported these problems:
  Domain: www.second.earnanswers.com
  Type:   dns
  Detail: DNS problem: NXDOMAIN looking up A for www.second.earnanswers.com - check that a DNS record exists for this domain; DNS problem: NXDOMAIN looking up AAAA for www.second.earnanswers.com - check that a DNS record exists for this domain

Hint: The Certificate Authority failed to verify the temporary nginx configuration changes made by Certbot. Ensure the listed domains point to this nginx server and that it is accessible from the internet.

Cleaning up challenges
Some challenges have failed.
Ask for help or search for solutions at https://community.letsencrypt.org. See the logfile /var/log/letsencrypt/letsencrypt.log or re-run Certbot with -v for more details.

Records:
second XXX:XXX::XXXX:XXXX:XXXX:XXXX Default
second XXX.XX.XX.XXX Default

I go on linode to add a AAAA record for the second subdomain for the IPv6 address (It was missing).
I did it 10 min ago. Tried to regenerate the certificates, and same issue.

Do I need to wait 24h of so, for the changes to "propagate"?

Appreciate the assistance.

Carrot.