RFC2616 is obsolete, see <a href="http:&#x2F;&#x2F;httpwg.github.io&#x2F;specs&#x2F;rfc7231.html" rel="nofollow">http:&#x2F;&#x2F;httpwg.github.io&#x2F;specs&#x2F;rfc7231.html</a> (and friends, as referenced).