A cooling apparatus of an exhaust gas recirculation system includes a first cooling portion, made of a first material, that receives recirculation exhaust gas; and a second cooling portion, made of a second, different material, that receives the recirculation exhaust gas from the first cooling portion and exhausts the recirculation exhaust gas out of the apparatus. The design structure may control heat generation in a multi-core processor. The proxy server is programmed for maintaining a log of all content fetched including a time of the fetch and the requesting end user browser, and storing associations between content fetched within a fixed time period by the same requesting end user browser.