For testing purposes I have and SSL certificate set up on a dev site where the domain does not match SSL domains valid for that certificate.
Would it still be possible to validate credit cards with Authorize.net even though the certificate domain is invalid?
It depends on how you are communicating with authorize.net, but when I did it, I sent a request from my server to their’s to authorize the transaction. So, they never saw my SSL certificate, because they never sent a request to my web server. So, to answer your question, assuming you are authorizing the transaction by initiating an SSL connection to their server, then it shouldn’t matter one bit if you have a valid SSL cert or not.
That of course was the technical answer. As for what their rules might be, I couldn’t say.