As we reported earlier, the rules for validating a certificate will change this year.
From November 22th 2021 onwards it will no longer be possible to validate a wildcard certificate by placing a file on your website. Validation via e-mail or via DNS is still possible.
Other certificates can still be validated via a file on your website, but the file must be placed on the exact subdomain. It is currently possible to validate a subdomain of a multidomain certificate through the root domain. So: *.yourname.be, www.yourname.be, leads.yourname.be,mail.yourname.be – and all possible other subdomains. If yourname.be was validated, all subdomains were also validated.
Also with a PositiveSSL, the www domain is automatically validated with validation of the main domain.
These options will disappear from November 22th 2021 onwards. For each certificate, each subdomain will have to be validated separately, either via email or via DNS.