An HTTP client must always assume URL paths and query strings are case-sensitive. You can't rely on the bing.com web servers always returning the same resource

An HTTP client must always assume URL paths and query strings are case-sensitive. You can't rely on the bing.com web servers always returning the same resource for http://www.bing.com/search?q=test http://www.bing.com/search?q=test and http://www.bing.com/Search?q=test http://www.bing.com/Search?q=test just because the default filesystem for their OS is case-insensitive today. Actually it's unlikely the main entry point for their search engine is a file named "search" in some top-level directory. The only way for an author to tell you many URLs are equivalent is to use "301 Moved Permanently" responses to the canonical one from all the others, and Bing doesn't do that.