为什么 Chrome 会发送 HEAD 请求？日志中的示例：
2013-03-04 07:43:51 W3SVC7 NS1 GET /page.html 80 - *.*.*.* HTTP/1.1 Mozilla/5.0+(Windows+NT+6.1;+WOW64)+AppleWebKit/537.22+(KHTML,+like+Gecko)+Chrome/25.0.1364.97+Safari/537.22
2013-03-04 07:43:51 W3SVC7 NS1 HEAD / - 80 - *.*.*.* HTTP/1.1 Mozilla/5.0+(Windows+NT+6.1;+WOW64)+AppleWebKit/537.22+(KHTML,+like+Gecko)+Chrome/25.0.1364.97+Safari/537.22
我有一个禁止系统，这个头部请求真的很烦人，它的发生与 GET 请求完全相同。
它的性质是什么？任何帮助表示赞赏。
ps：我注意到头部请求都只针对我的主页。
RFC 2616规定：
9.4 HEAD
The HEAD method is identical to GET except that the server MUST NOT
return a message-body in the response. The metainformation contained
in the HTTP headers in response to a HEAD request SHOULD be identical
to the information sent in response to a GET request. This method can
be used for obtaining metainformation about the entity implied by the
request without transferring the entity-body itself. This method is
often used for testing hypertext links for validity, accessibility,
and recent modification.
The response to a HEAD request MAY be cacheable in the sense that the
information contained in the response MAY be used to update a
previously cached entity from that resource. If the new field values
indicate that the cached entity differs from the current entity (as
would be indicated by a change in Content-Length, Content-MD5, ETag
or Last-Modified), then the cache MUST treat the cache entry as
stale.
很可能它正在尝试验证客户端 cookie/会话对服务器有效。