cookie从哪里来？
最近研究请求信息头，发现有些网站第一次访问时，header里面就会有cookie，即使将本地所有cookie删除后，访问这些网站，仍然可以看到cookie，请问各位，这些cookie从何处来？ 如何设置或提取这些cookie


新浪www.sina.com.cn的第一次访问时请求消息中的cookie(抓包工具httpwatch)
GET / HTTP/1.1
Accept: */*
Accept-Language: zh-CN
User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET4.0C; .NET4.0E)
Accept-Encoding: gzip, deflate
If-Modified-Since: Sun, 19 Aug 2012 23:05:12 GMT; length=641199
Host: www.sina.com.cn
Connection: Keep-Alive
Cookie: U_TRS1=000000b4.e6d16978.5030e230.f4972cd9; UOR=,login.sina.com.cn,; SINAGLOBAL=9287035968646.261.1345381736468; ULV=1345417577836:5:5:5:211677441128.002.1345417577717:1345413627023; _u_poll=blog%2C1%2C50; vjuids=-bf6123461.1393f0eb24c.0.d2a90acaf63bc8; vjlast=1345415926; U_TRS2=000000ec.2f965837.5031716a.99d2543b; Apache=211677441128.002.1345417577717; _s_upa=1; SSCSum=9; SinaRot//=39; rpb_1_1=1345415923405; CoupletMediahttp://www.sina.com.cn/=1; rpb_1_2=1345417582950; sinaVideoAd=played; iCast2_55592_1885=0_9999_1440; _iCast2_55592_1885=1; iCast2_55592_1885hO=0_9999_20160; _iCast2_55592_1885hO=1; mv2012_sina_lb=0


百度www.baidu.com的第一次访问时请求消息中的cookie(抓包工具httpwatch)
GET / HTTP/1.1
Accept: */*
Accept-Language: zh-CN
User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET4.0C; .NET4.0E)
Accept-Encoding: gzip, deflate
Host: www.baidu.com
Connection: Keep-Alive
Cookie: BAIDUID=346FF479B6FC858E0F75D93E43B6BCE4:FG=1; BDUT=oyg9346FF479B6FC858E0F75D93E43B6BCE4138fb2748790; BDREFER=%7Burl%3A%22http%3A//news.baidu.com/%22%2Cword%3A%22%22%7D; MAP_SAMPLING=tab_ex00


------解决方案--------------------
1，你真的完全清空了吗？清空所有网站的，
2，你要看第一个请求的url，
------解决方案--------------------
控制面板—>Internet选项,在这里清除Internet浏览历史记录，把所有都选上操作下。然后你再去看看