1. An invalidation tracker system for tracking invalidation messages in a caching architecture, the invalidation tracker system comprising: a processor for tracking the invalidation messages in the caching architecture, wherein the caching architecture includes a plurality of levels and each of the plurality of levels comprises at least one server, and wherein invalidation messages are communicated from one of the plurality of levels to another one of the plurality of levels in order to send the invalidation messages to all of servers in the caching architecture, and wherein the servers each include a corresponding key logger for locally storing all the invalidation messages received by each server; and a computer storage medium including a plurality of instructions that, when executed by the processor, cause the invalidation tracker system to: record all of the invalidation messages communicated to the servers in the caching architecture to form a set of sent invalidation messages, wherein the invalidation messages are for invalidating content within the caching architecture; determine the invalidation messages received at each of the servers in the caching architecture and comparing the invalidation messages with the set of sent invalidation messages to identify one or more undelivered invalidation messages; check the corresponding key logger for each of the servers one level at a time within the caching architecture to determine the invalidation messages received at each of the plurality of levels in the caching architecture; identify a specific level within the caching architecture where the one or more undelivered invalidation messages were not delivered based on comparing the invalidation messages received at each of the plurality of levels in the caching architecture with the set of sent invalidation messages, wherein the invalidation tracker system determines the specific level within the caching architecture by checking the key logger for each of the servers one level at a time within the caching architecture; and resend the one or more undelivered invalidation messages to an appropriate server in the caching architecture.