I setup a custom domain on my GitHub page, so if I navigate to https://username.github.io/repo-name/ it will redirect to https://subdomain.example.com. Then I remove that custom domain. It has been a day and Firefox still cache the redirection. In this post Is it possible to forget just a subdomain / any idea what might resolve this glitch? : r/firefox it is said that you can’t forget a subdomain. This indicates that all subdomains of a domain are aggregated as if they are one domain. Is that correct? Is this Firefox only or all browsers as well? And in general, how does subdomain caching work?