What is memcache?
You can probably figure out memcache's purpose from the name, memory caching, or storing memory. Memcache is a key-value store used by websites to store and retrieve information rapidly, without reloading the information. Designed to reduce database load in dynamic web applications, it can be used to save website content, images, even whole pages.
How does memcache work?
Data is stored and filed by a unique name on the memcached server, waiting to be called back by that unique name when you need it. An allocated RAM space is held by the memcached server for this purpose, making it much faster to retrieve the data from RAM than from a hard drive or disk.
What's up with memcache vs. memcached?
Memcache and memcached have different authors and slightly different ways of storing value. Memcache considers each value a string, while memcached stores each distinct original value type.
What is Memcrashed?
Memcrashed is a form of DDoS (Distributed Denial of Service) attack that uses memcache as a UDP (User Datagram Protocol) reflection attack vector (learn more). That means bad actors spoof source addresses for UDP traffic in order to trick internet-facing services into sending hundreds of thousands of responses to fake requests. Because memcache can amplify response traffic by a massive amount, it's an attractive attack vector for criminals looking to bring the Internet to a crawl.