在 RFC 7234 里描述啟發(fā)式新鮮度:
If the response has a Last-Modified header field (Section 2.2 of [RFC7232]), caches are encouraged to use a heuristic expiration value that is no more than some fraction of the interval since that time. A typical setting of this fraction might be 10%.
應(yīng)該是說如果過有 Last-Modified 這個頭妈嘹,那么啟發(fā)式新鮮度的時間一般取 Last-Modified 的10%脖旱,而不是有 Last-Modified 才會使用 啟發(fā)式新鮮度 來設(shè)置過期時間。