Difference between www.sub.example.com and sub.example.com

Question

I want to know the difference between these two links to my site:

• My site https://rahul62888282.000webhostapp.com is working as supposed.
• https://www.rahul62888282.000webhostapp.com (with www) is showing me a privacy error.

Answer 1

Wildcard certificates covers only one level of subdomains. RFC 2818, 3.1:

Matching is performed using the matching rules specified by RFC2459. If more than one identity of a given type is present in the certificate (e.g., more than one dNSName name, a match in any one of the set is considered acceptable.) Names may contain the wildcard character * which is considered to match any single domain name component or component fragment. E.g., *.a.com matches foo.a.com but not bar.foo.a.com.

Your *.000webhostapp.com matches rahul62888282.000webhostapp.com, not its subdomains.