In most cases, the keys of query strings (a part of the URL, typically after ?) are case-sensitive. This means that when processing URLs and query strings, keys such as "ID" and "id" are treated as two distinct parameters.
For example, if your URL is:
http://example.com/api?Id=123&ID=456
In this URL, Id and ID are two distinct parameters that can hold different values (123 and 456). If your server or application's query string parser is case-sensitive (which is the default for most web servers and frameworks), it will treat these parameters as separate inputs.
However, it's worth noting that some systems or programming frameworks may provide configuration options to ignore case sensitivity in query strings. But the standard practice is to treat keys as case-sensitive, so when developing or designing APIs or web applications, it's recommended to explicitly specify this to avoid confusion or errors.