Let’s Encrypt has recently started supporting wildcard certificates using its new ACME2 protocol. This means that you can have a single wildcard certificate like *.asknetsec.com and use it on all the other sub-domains like blog.askenetsec.com, email.asknetsec.com.
This makes is very easy to manage certificates for different sub-domains. Until now each sub-domain needed its own certificate generated for the specific sub-domain.