So, Host Named Site Collections are the new thing. You’ve created your web application and created a host named site collection through PowerShell. You browse to the site and it renders nicely. Yet when you expect to see the site, you get the standard SharePoint screen which tells you that you don’t have access to that site. This can be resolved easily. Check your IIS bindings. You forgot to remove them. So even though you have a DNS pointing to *.myhncsites.contoso.com and you created a site banzai.myhncsites.contoso.com your IIS bindings need to be modified so that there are no host headers defined.