Let's Encrypt Wildcard Certificate Note

wget https://dl.eff.org/certbot-auto
chmod a+x certbot-auto
./certbot-auto --server https://acme-v02.api.letsencrypt.org/directory -d domain.com -d *.domain.com --manual --preferred-challenges dns-01 certonly

Note: need to specific domain.com and *.domain.com together if you want to issue a single certificate for both.