1. These more complex relationships between caches allow different organizations to be peers
Caches are connected for a win-win situation. Caches that provide optional peer-to-peer support are called sibling caches
cache). HTTP does not support sibling caching, so people use some protocol to
Extended, such as the Internet Cache Protocol (ICP) and the Hypertext Cache Protocol
议（HyperText Caching Protocol，HTCP）。
2. A MIME type is a textual markup that represents a main object type and a specific subtype, intermediate
separated by a slash.