IP Address based User Persistence and/or Stickiness works for the users whose public IP address is fixed during user session and their ISP is not using stateless forward proxies to serve the http/https request to the outside world.

Cookies based User Persistence and/or Stickiness works in all the cases where even an ISP provider like AOL who uses stateless forward proxies to serve the http/https request for their customer for better user experience. The implementation of the forward proxies to serve http/https request from enterprise networks is also used not only for better performance and network resource optimization but for better security and monitoring.

Cookie based User Persistence and/or Stickiness will always works even if the stateless forward http/https proxy is used to serve the end users. It recommended that we use User Cookie over IP Address.