About ICP

The Internet Cache Protocol (ICP) is an object location protocol that enables caches to communicate with one another. Caches can use ICP to send queries and replies about the existence of cached URLs and about the best locations from which to retrieve those URLs. In a typical ICP exchange, one cache will send an ICP query about a particular URL to all neighboring caches. Those caches will then send back ICP replies that indicate whether or not they contain that URL. If they do not contain the URL, they send back a “MISS.” If they do contain the URL, they send back a “HIT.”