My company sells application servers to customers; 90% of thoses servers are offline in dedicated network. We currently have a self signed certificate generated automatically according to the ip of the server.
Will it be possible to buy a wildcard certificate and use it on all the servers locally ?
Let's say we buy a certificate for *.mydomain.com (mydomain.com will be a real domain that we own). The certificate is installed on the servers. And on the local network we have a dns (or a modified host file) that map the servers's ip to a subdomain . Will it be ok ? We just need to avoid the big warning in the browsers saying that the certificate is invalid. No need for EV certification or all this fancy things.
I tried it with let's encrypt and a standard certificate (not wildcard) and a modifed host file and it seems fine, but will it be ok with the "big" CA like Globalsign, Thwathe, etc ... ?