An Internet address is only case sensitive for everything after the domain name.
For example, it does not matter if you use uppercase or lowercase with “computerhope.com,” it still reaches the same page.
However, when typing the name of the page, file, or directory in the URL, it is case sensitive.
Are email domains case sensitive?
The domain name part of an email address is case insensitive (i.e. the case does not matter). The local mailbox part (the username), however, is case sensitive.
Is FQDN case sensitive?
Host names (or ‘labels’), such as example.com are case-insensitive. DNS record types, such as ‘A’, and ‘MX’ are case sensitive. Values in TXT and SPF records are case sensitive.
Can a URL be case sensitive?
There may be URLs, or parts of URLs, where case doesn’t matter, but identifying these may not be easy. Users should always consider that URLs are case-sensitive. Domain names are case insensitive according to RFC 4343. The rest of URL is sent to the server via the GET method.
Are subdomains case sensitive?
Nope, domains and subdomains are always lowercase. The DNS system is always case insensitive.