Trailer - HTTP
these header fields are disallowed: message framing headers (e.g., transfer-encoding and content-length), routing headers (e.g., host), request modifiers (e.g., controls and conditionals, like cache-control, max-forwards, or te), authentication headers (e.g., authorization or set-cookie), or content-encoding, content-type, content-range, and trailer itself.

HTTP headers - HTTP
max-forwards cookies cookie contains stored http cookies previously sent by the server with the set-cookie header.

TRACE - HTTP
the final recipient is either the origin server or the first server to receive a max-forwards value of 0 in the request.