Say, one wants to create multi-level sub-domains, so I was wondering if this type of SSL even exists? I know Letsencrypt and few other paid SSL have wildcard feature but I believe it covers only wildcard sub-domains like *.domain.tld, *.sub.domain.tld or *.sub.sub.domain.tld which all can be requested as one cert but is there any out there that covers domain.tld and all of its multi-level sub-domains certifying that the domain and all its sub-domain in which ever level are secure, which may be equivalent to something like *.*.*.domain.tld in one cert? I read what RFC says and I also seems to find none sells such SSL cert so far, so if anybody confirm that there is no such thing, I can relieve myself from ever thinking about it.
What is that, offhand? I only know that a few years ago, trying to use a *.domain.tld wildcard cert didn't work for x.y.domain.tld; I don't remember seeing any other option at that time (which doesn't exactly answer your question, but...).
There are several as mentioned in stackexchange discussion but RFC 2818 and RFC 6125 are basically what I read because they are the main reference in that discussion. *.*.domain.tld SSL certs didn't work, though may be created using openssl, most probably because it is not supported by the browsers due to RFC 6125. *.domain.tld also didn't work for x.y.domain.tld.
