国内使用Nginx 运行静态HTML页、图片、FLV视频的网站

1、网易新闻（http://news.163.com/）：nginx/0.6.31
[root@new-host ~]# curl –headhttp://news.163.com/
HTTP/1.0 200 OK
Server: nginx/0.6.31
Date: Wed, 18 Jun 2008 01:17:04 GMT
Content-Type: text/html; charset=GBK
Expires: Wed, 18 Jun 2008 01:20:04 GMT
Cache-Control: max-age=180
X-Cache: MISS from cgi-gzip.163.com
Content-Length: 259923
Vary: Accept-Encoding
Age: 74
X-Cache: HIT from news.163.com
Connection: close
2、酷6网（http://www.ku6.com/）视频服务器：nginx/0.5.36
[root@new-host ~]# curl –headhttp://video.ku6.com/
HTTP/1.1 404 Not Found
Server: nginx/0.5.36
Date: Wed, 18 Jun 2008 01:50:06 GMT
Content-Type: text/html; charset=utf-8
Connection: keep-alive
Last-Modified: Sun, 05 Aug 2007 09:49:48GMT
Accept-Ranges: bytes
Content-Length: 18782
Vary: Accept-Encoding
X-Cache: MISS from CDN-TJ-249
3、豆瓣网（http://www.douban.com/）：nginx
[root@new-host ~]# curl –headhttp://www.douban.com/
HTTP/1.1 200 OK
Server: nginx
Date: Wed, 18 Jun 2008 01:56:58 GMT
Content-Type: text/html; charset=utf-8
Status: 200 OK
Content-Length: 30106
Expires: Sun, 1 Jan 2006 01:00:00 GMT
Pragma: no-cache
Cache-Control: must-revalidate, no-cache,private
Set-Cookie: bid=”rAlrIPo2jl4″;path=/; domain=.douban.com; expires=Thu, 01-Jan-2009 00:00:00 GMT
4、新华网RSS订阅频道（http://rss.xinhuanet.com/）：nginx
[root@new-host ~]# curl –headhttp://rss.xinhuanet.com/
HTTP/1.1 200 OK
Server: nginx
Date: Wed, 18 Jun 2008 01:18:00 GMT
Content-Type: text/xml
Content-Length: 4592
Last-Modified: Mon, 26 Jun 2006 09:33:54GMT
Connection: keep-alive
Expires: Wed, 18 Jun 2008 01:24:00 GMT
Cache-Control: max-age=360
Accept-Ranges: bytes
5、迅雷安全中心（http://safe.xunlei.com/）：nginx/0.6.31
[root@new-host ~]# curl –headhttp://safe.xunlei.com/
HTTP/1.1 200 OK
Server: nginx/0.6.31
Date: Wed, 18 Jun 2008 02:05:54 GMT
Content-Type: text/html; charset=gb2312
Content-Length: 13060
Last-Modified: Thu, 12 Jun 2008 12:13:03GMT
Connection: keep-alive
Keep-Alive: timeout=30
Expires: Wed, 25 Jun 2008 02:05:54 GMT
Cache-Control: max-age=604800
Accept-Ranges: bytes
6、腾讯3G下载（http://down.3g.qq.com/）：nginx/0.5.33
[root@new-host ~]# curl –head http://down.3g.qq.com/
HTTP/1.1 403 Forbidden
Server: nginx/0.5.33
Date: Thu, 19 Jun 2008 05:50:44 GMT
Content-Type: text/html
Content-Length: 169
Connection:keep-alive

请问楼主，这些是如何知道的？PING出来的吗？