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What happens when a web server is using cookies?
Literal
Web server [subj-が] cookies [obj-を] utilizing case [topic-は] how become [polite-のでしょうか].
クッキー is the loanword for browser cookies. 利用している場合 'in the case where X is using' frames the condition. どうなるのでしょうか 'what happens / what will become of it' is the polite speculative question form. A clean, technical-explainer question.