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User goes to shoes.com, which loads ads from adserver.com, which sets a tracking cookie on domain adserver.com User goes to news.com, which loads ads from adse

by theamk 6y ago

User goes to shoes.com, which loads ads from adserver.com, which sets a tracking cookie on domain adserver.com User goes to news.com, which loads ads from adserver.com. Adserver.com sees the cookie, and shows the ads about shoes. If you do everything on the server side, shoes.com won't be able to place a global tracking cookie. So when the user goes to news.com, they'll have to see the generic ad, and not a targeted one.

ffpip 6y ago
User goes to shoes.com. Adserver.shoes.com acts as frontend for adserver.com. Adserver.com sends a cookie and adserver.shoes.com sets it. User goes to news.com. adserver.news.com loads ads from adserver.com . Adserver.com checks cookie from adserver.shoes.com and and generates ads server side and shows it with the news.
- theamk 6y ago
  > Adserver.com checks cookie from adserver.shoes.com 1. This is not possible from server-side. The way cookies work, cookies set by adserver.shoes.com are only visible from documents hosted on *.shoes.com domains. And if the tracking is done client-side, by image, iframe or some other remote call, then this is trivially detected and blocked by adblocker. 2. How did "adserver.com" knew to check for "adserver.shoes.com" cookies? there might be hunderds clients, and trying to load cookies from every domain (adserver.shoes.com, adserver.computers.com, adserver.travel-to-india.com and so on) will take way too long.