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Also known as: history
An index of every Message-ID the server has seen recently, with the article's arrival time and storage location. Its purpose is duplicate rejection: when a peer offers an article by CHECK or IHAVE, the server looks the ID up here and declines anything already held. It also drives expiry. On a busy transit server it holds tens of millions of entries.
Browse all terms in Protocol & Server Infrastructure, or see the full Usenet glossary.