IIS HTML, CSS, Script, 图片等静态文件不更新问题

文件已经更新到站点，但客户端访问仍然没有更新，主要是各种静态文件。
网关代理服务器缓存的可能性比较大，应该先检查这个原因。
代理服务器缓存还有一些其它表现，本地访问可以看到更新的效果；同一个网段、IE设置局域网访问不走代理，也能看到更新效果；客户端直接使用url访问静态文件（html页面、css文件、脚本等），获取到的是未更新的，在服务器上更新文件名字，客户端使用新的文件名访问，能够获取到更新后的文件。

Tag Name	Example(s)	Description
Author	<META NAME="AUTHOR" CONTENT="Tex Texin">	The author's name.
cache-control	<META HTTP-EQUIV="CACHE-CONTROL" CONTENT="NO-CACHE">	HTTP 1.1. Allowed values = PUBLIC | PRIVATE | NO-CACHE | NO-STORE. Public - may be cached in public shared caches Private - may only be cached in private cache no-Cache - may not be cached no-Store - may be cached but not archived The directive CACHE-CONTROL:NO-CACHE indicates cached information should not be used and instead requests should be forwarded to the origin server. This directive has the same semantics as the PRAGMA:NO-CACHE. Clients SHOULD include both PRAGMA:NO-CACHE and CACHE-CONTROL:NO-CACHE when a no-cache request is sent to a server not known to be HTTP/1.1 compliant. Also see EXPIRES. Note: It may be better to specify cache commands in HTTP than in META statements, where they can influence more than the browser, but proxies and other intermediaries that may cache information.
Content-Language	<META HTTP-EQUIV="CONTENT-LANGUAGE" CONTENT="en-US,fr">	Declares the primary natural language(s) of the document. May be used by search engines to categorize by language.
CONTENT-TYPE	<META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html; charset=UTF-8">	The HTTP content type may be extended to give the character set. It is recommended to always use this tag and to specify the charset.
Copyright	<META NAME="COPYRIGHT" CONTENT="&copy; 2004 Tex Texin">	A copyright statement.
DESCRIPTION	<META NAME="DESCRIPTION" CONTENT="...summary of web page...">	The text can be used when printing a summary of the document. The text should not contain any formatting information. Used by some search engines to describe your document. Particularly important if your document has very little text, is a frameset, or has extensive scripts at the top.
EXPIRES	<META HTTP-EQUIV="EXPIRES" CONTENT="Mon, 22 Jul 2002 11:12:01 GMT">	The date and time after which the document should be considered expired. An illegal EXPIRES date, e.g. "0", is interpreted as "now". Setting EXPIRES to 0 may thus be used to force a modification check at each visit. Web robots may delete expired documents from a search engine, or schedule a revisit. HTTP 1.1 (RFC 2068) specifies that all HTTP date/time stamps MUST be generated in Greenwich Mean Time (GMT) and in RFC 1123 format. RFC 1123 format = wkday "," SP date SP time SP "GMT" wkday = (Mon, Tue, Wed, Thu, Fri, Sat, Sun) date = 2DIGIT SP month SP 4DIGIT ; day month year (e.g., 02 Jun 1982) time = 2DIGIT ":" 2DIGIT ":" 2DIGIT ; 00:00:00 - 23:59:59 month = (Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec)
Keywords	<META NAME="KEYWORDS" CONTENT="sex, drugs, rock & roll">	The keywords are used by some search engines to index your document in addition to words from the title and document body. Typically used for synonyms and alternates of title words. Consider adding frequent misspellings. e.g. heirarchy, hierarchy.
PRAGMA NO-CACHE	<META HTTP-EQUIV="PRAGMA" CONTENT="NO-CACHE">	This directive indicates cached information should not be used and instead requests should be forwarded to the origin server. This directive has the same semantics as the CACHE-CONTROL:NO-CACHE directive and is provided for backwards compatibility with HTTP/1.0. Clients SHOULD include both PRAGMA:NO-CACHE and CACHE-CONTROL:NO-CACHE when a no-cache request is sent to a server not known to be HTTP/1.1 compliant. HTTP/1.1 clients SHOULD NOT send the PRAGMA request-header. HTTP/1.1 caches SHOULD treat "PRAGMA:NO-CACHE" as if the client had sent "CACHE-CONTROL:NO-CACHE". Also see EXPIRES.
Refresh	<META HTTP-EQUIV="REFRESH" CONTENT="15;URL=http://www.I18nGuy.com/index.html">	Specifies a delay in seconds before the browser automatically reloads the document. Optionally, specifies an alternative URL to load, making this command useful for redirecting browsers to other pages.
ROBOTS	<META NAME="ROBOTS" CONTENT="ALL"> <META NAME="ROBOTS" CONTENT="INDEX,NOFOLLOW"> <META NAME="ROBOTS" CONTENT="NOINDEX,FOLLOW"> <META NAME="ROBOTS" CONTENT="NONE">	CONTENT="ALL | NONE | NOINDEX | INDEX| NOFOLLOW | FOLLOW | NOARCHIVE" default = empty = "ALL" "NONE" = "NOINDEX, NOFOLLOW" The CONTENT field is a comma separated list: INDEX: search engine robots should include this page. FOLLOW: robots should follow links from this page to other pages. NOINDEX: links can be explored, although the page is not indexed. NOFOLLOW: the page can be indexed, but no links are explored. NONE: robots can ignore the page. NOARCHIVE: Google uses this to prevent archiving of the page. See http://www.google.com/bot.html
GOOGLEBOT	<META NAME="GOOGLEBOT" CONTENT="NOARCHIVE">	In addition to the ROBOTS META Command above, Google supports a GOOGLEBOT command. With it, you can tell Google that you do not want the page archived, but allow other search engines to do so. If you specify this command, Google will not save the page and the page will be unavailable via its cache. See Google's FAQ.