Have you ever received a “This page is not protected” error while trying to access a web page? Maybe even your own web page? This may mean that the site, or your site, that you are trying to access has an SSL Certificate Name Mismatch error. In simplest of forms, this means that the name for the website on the certificate doesn’t match the name in the URL/Address Bar.
For example: typing in www.example.com, when the certificate for the site is for explicitly https://example.com
This is most likely a cause of not having the right common name, or not having the correct Subject Alternative Name (SAN) on the website’s certificate.
There are two main parts of the certificate that are important when dealing with this specific issue. The Subject field, and the Subject Alternative Name field, both of which are accessed in the Details of a certificate.
As the pictures show, Experts Exchange’s certificate has a Common Name of: experts-exchange.com, and two SANs: experts-exchange.com & *.experts-exchange.com.
For those unfamiliar, the asterisk (*) represents a wildcard, which means that anything can go in its place, in this case, a sub-domain. Using this wildcard we cover any cases that might cause a name mismatch error when entering www.expert-exchange.com and https://experts-exchange.com as well as other URLs.
Google is a great example of a company that uses wildcard sub-domains.
As they have sub-domains like drive.google.com, hangouts.google.com, and many more, it makes sense that they would wildcard their sub-domains. Note that they can also use wildcards on completely different domains(ie. Google.co.jp & google.co.uk). They also have their own Internet Authority, which allows them to create their own certificate.
While having a wildcard sub-domain can be a hassle-free solution to many name mismatch problems, it is more expensive to obtain a wildcard certificate.
According to GoDaddy’s standard Certificate pricing: a One Site certificate is $75 a year, a certificate that will protect one domain and up to 5 SANs for $169 per year, while a wildcard certificate that protects all subdomains for 1 domain is $350 per year.
If you manage a site that is experiencing name mismatch errors:
I hope that this article may help you if you, or your site visitors, are receiving this error when accessing your site.