4 ms·

Can't their servers contact the mothership? And cache potential ads? I don't even mind the ads so much as the delay.

icebraining 11y ago
Contacting the mothership doesn't help. The way it works is that an ad network loaded by site A sets a cookie with a new random ID. When you go to site B with the same ad network, since the ads are served from the same domain (the ad network's), it can read the cookie with the ID and link the two website visits. If ads came from the sites own domains, this wouldn't work.
- tosseraccount 11y ago
  They know your domain, your IP address, your referer, your screen size, your OS, your browser version, your supported MIME types, your port number, your plugins, your ISP. That should be enough information for cooperating servers to target an ad.
  - icebraining 11y ago
    Often yes, but that breaks easily. Referers are often not sent nowadays. Screen size and OS are often similar. Browsers now auto-update, so the versions are increasingly the same, along with plugins, which are getting rarer. Port numbers vary by connection, so you can't match them. IP address don't work well for people behind NAT, which is particularly common for mobile connections, which often have carrier-grade NAT[1], and for workplace/university/school networks. Say you have two users on Macbook Airs using auto-updating Chrome (which has bundled Flash) in the same office or university, and both came in through Google. Is this an unlikely scenario? Not really. [1] https://en.wikipedia.org/wiki/Carrier-grade_NAT https://en.wikipedia.org/wiki/Carrier-grade_NAT
  - jasode 11y ago
    >They know your domain, your IP address, [...] Yes, they can try to "fingerprint" your browser into a unique hash but that method is more reliable for desktops than mobile phones. Imagine a dozens of customers with identical iPhones sharing the wifi at Starbucks or the airport. (Everybody has the same ip address.) Sniffing for unique markers such as counting installed fonts and/or plugins isn't going to work on smartphones like it does on deskttops. Therefore, generating a cookie with an id is more reliable. Of course, people can negate that by configuring their phones to block cookies but it appears that most consumers don't do it (probably because it breaks other things such as banking, sports, etc websites.) Since advertising revenue from mobiles is growing faster than desktops, and in some cases exceeds it (Twitter mobile ads), it doesn't look like ad networks will favor fingerprinting over cookies. (That's not to say some sophisticated ad networks don't blend both techniques.)
    - icebraining 11y ago
      Mobile Safari does block third-party cookies by default, which prevents ad networks from setting these tracking cookies.

Contacting the mothership doesn't help. The way it works is that an ad network loaded by site A sets a cookie with a new random ID. When you go to site B with the same ad network, since the ads are served from the same domain (the ad network's), it can read the cookie with the ID and link the two website visits. If ads came from the sites own domains, this wouldn't work.

tosseraccount 11y ago
They know your domain, your IP address, your referer, your screen size, your OS, your browser version, your supported MIME types, your port number, your plugins, your ISP. That should be enough information for cooperating servers to target an ad.
- icebraining 11y ago
  Often yes, but that breaks easily. Referers are often not sent nowadays. Screen size and OS are often similar. Browsers now auto-update, so the versions are increasingly the same, along with plugins, which are getting rarer. Port numbers vary by connection, so you can't match them. IP address don't work well for people behind NAT, which is particularly common for mobile connections, which often have carrier-grade NAT[1], and for workplace/university/school networks. Say you have two users on Macbook Airs using auto-updating Chrome (which has bundled Flash) in the same office or university, and both came in through Google. Is this an unlikely scenario? Not really. [1] https://en.wikipedia.org/wiki/Carrier-grade_NAT https://en.wikipedia.org/wiki/Carrier-grade_NAT
- jasode 11y ago
  >They know your domain, your IP address, [...] Yes, they can try to "fingerprint" your browser into a unique hash but that method is more reliable for desktops than mobile phones. Imagine a dozens of customers with identical iPhones sharing the wifi at Starbucks or the airport. (Everybody has the same ip address.) Sniffing for unique markers such as counting installed fonts and/or plugins isn't going to work on smartphones like it does on deskttops. Therefore, generating a cookie with an id is more reliable. Of course, people can negate that by configuring their phones to block cookies but it appears that most consumers don't do it (probably because it breaks other things such as banking, sports, etc websites.) Since advertising revenue from mobiles is growing faster than desktops, and in some cases exceeds it (Twitter mobile ads), it doesn't look like ad networks will favor fingerprinting over cookies. (That's not to say some sophisticated ad networks don't blend both techniques.)
  - icebraining 11y ago
    Mobile Safari does block third-party cookies by default, which prevents ad networks from setting these tracking cookies.