2. Even with HTTPS, ISPs can still see the domains that their subscribers visit. When a site does use HTTPS, the Upturn team explained that an “ISP cannot see the URLs and content in unencrypted
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I would wager that those ISP's that do not have Carnivore installed by the DOJ just overwrite their existing logs every so often, not unlike a web server that is setup to keep two server logs, one monthly log and the previous month. Server logs are HUGE files and I seriously doubt that ISP's go to the expense of buying new hard drives often.
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Is Your ISP Spying On You? | PCWorld
UK ISP logs | Wilders Security Forums Jan 01, 2010 Does comcast keep a file of user's visited websites