The reply is generated by the server in question, using information available to it. Essentially, the point here is that WhatsApp is "clicking" the link (to ge

The reply is generated by the server in question, using information available to it. Essentially, the point here is that WhatsApp is "clicking" the link (to generate a preview) with a resulting connection from the client's device, without user interaction. So you can send a link to a server you control and harvest the recipient's client device IP, without the need for them to click on it.