Invalidation is carried out by changing the application data, which in turn marks the information received by the client as out-of-date.
When the client requests the data again, it is fetched from the application and stored in the caching proxy.
[1] A reference to the cached content is added to a blacklist (or ban list).
One alternative is to expire the cached content quickly by reducing the time-to-live (TTL) to a very low value.
These alternatives can cause issues, as they create high load on the application due to more frequent requests for information.