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The Cylon Resurrection Hub is a space-borne facility which coordinates the resurrection process among all of the Cylon resurrection ships and downloading facilities, with what appears to be a substantial operational range between itself and the rest of the Cylon fleet. It was designed by the Final Five (TRS: "No Exit").
Additionally, the Hub itself functions as a resurrection facility, containing resurrection tanks and a large number of spare bodies. As the control center of all resurrections, it is vital to Cylon society. As a safeguard, the Hub periodically jumps to new locations and relays its position to the baseships' Hybrids once completed. The Resurrection Hub is also where boxed Cylon consciousnesses are stored.
The fact that several Cylons such as Gina Inviere face permanent death in the absence of a Resurrection Ship before the Hub's destruction, suggests that the Resurrection Ships act as a kind of 'booster' for the Hub's downloading effect, and the Hub's range and ability to download Cylons' consciousnesses on its own is limited; otherwise no Cylon would have died permanently before this point. Indeed, after obtaining information from Inviere, Gaius Baltar stated that the Resurrection Ships were created for the purpose of extending the range of the normal downloading process (TRS: "Resurrection Ship, Part I").
At the start of the Cylon Civil War, Natalie plans to unbox D'Anna Biers in the hopes of learning the identities of the Final Five (TRS: "The Ties That Bind"). However, the Cavil faction retains possession of the Hub. When Demetrius returns to the Fleet with the renegade baseship, Natalie offers Admiral Adama and President Roslin the chance to destroy the Hub in return for their help unboxing D'Anna. Before the plan is carried out, Natalie is shot by Sharon Agathon and the basestar jumps after Roslin, determined to get some answers about her visions, has the Hybrid reconnected (TRS: "Guess What's Coming to Dinner?").
The Hybrid follows the Hub, jumping ever closer to it, and eventually catches up. In the ensuing Battle of the Resurrection Hub, an uneasy alliance of Cylons and Colonials attack the Hub, with rebel humanoid Cylon pilots towing powered-down Colonial Vipers behind Heavy Raiders in order to conceal them. Once untethered, the Vipers attack the Hub's FTL drives, stranding it. As the rebel baseship and Heavy Raiders engage the two defending baseships, Karl Agathon and a Number Eight board the Hub to retrieve the restored D'Anna Biers. Once their Raptor clears the Hub, the Vipers fire nuclear missiles, destroying the Hub and at least one of the nearby basestars (TRS: "The Hub").
With the Hub's destruction, the Cylons can no longer resurrect and will know permanent death. The Significant Seven are unable to replace the Hub because it is the Final Five's technology and only they knew how it worked. The Cavil/Simon/Doral faction now faces extinction because they cannot resurrect or reproduce (TRS: "No Exit"). Thanks to the destruction of the Hub and resurrection, Cavil's faction is finally destroyed by Galactica along with The Colony in the Battle of The Colony and they can't resurrect to come back for revenge. Among the confirmed dead from that battle are Cavil, Boomer, and Tory Foster. Later Samuel Anders dies as well. Those deaths are permanant due to the loss of resurrection and with Tory and Anders' deaths, there is no way for resurrection to be rebuilt. If any Cylon survived that cataclysmic battle, they eventually died out of natural causes without the Hub around to resurrect them in new bodies (TRS: "Daybreak, Part I", "Daybreak, Part II").