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23 <modulesynopsis metafile="mod_cache.xml.meta">
25 <name>mod_cache</name>
26 <description>Content cache keyed to URIs.</description>
27 <status>Extension</status>
28 <sourcefile>mod_cache.c</sourcefile>
29 <identifier>cache_module</identifier>
32 <note type="warning">This module should be used with care, as when the
33 <directive module="mod_cache">CacheQuickHandler</directive> directive is
34 in its default value of <strong>on</strong>, the <directive
35 module="mod_authz_host">Allow</directive> and <directive
36 module="mod_authz_host">Deny</directive> directives will be circumvented.
37 You should not enable quick handler caching for any content to which you
38 wish to limit access by client host name, address or environment
41 <p><module>mod_cache</module> implements an <a
42 href="http://www.ietf.org/rfc/rfc2616.txt">RFC 2616</a> compliant HTTP
43 content cache that can be used to cache either local or proxied content.
44 <module>mod_cache</module> requires the services of one or more storage
45 management modules. One storage management module is included in
46 the base Apache distribution:</p>
48 <dt><module>mod_disk_cache</module></dt>
49 <dd>implements a disk based storage manager.</dd>
52 <p>Content is stored in and retrieved from the cache using URI based keys. Content with
53 access protection is not cached.</p>
54 <p>Further details, discussion, and examples, are provided in the
55 <a href="../caching.html">Caching Guide</a>.</p>
57 <seealso><a href="../caching.html">Caching Guide</a></seealso>
59 <section id="related"><title>Related Modules and Directives</title>
62 <module>mod_disk_cache</module>
65 <directive module="mod_disk_cache">CacheRoot</directive>
66 <directive module="mod_disk_cache">CacheDirLevels</directive>
67 <directive module="mod_disk_cache">CacheDirLength</directive>
68 <directive module="mod_disk_cache">CacheMinFileSize</directive>
69 <directive module="mod_disk_cache">CacheMaxFileSize</directive>
74 <section id="sampleconf"><title>Sample Configuration</title>
75 <example><title>Sample httpd.conf</title>
77 # Sample Cache Configuration<br />
79 LoadModule cache_module modules/mod_cache.so<br />
81 <IfModule mod_cache.c><br />
83 LoadModule disk_cache_module modules/mod_disk_cache.so<br />
84 <IfModule mod_disk_cache.c><br />
86 CacheRoot c:/cacheroot<br />
87 CacheEnable disk /<br />
88 CacheDirLevels 5<br />
89 CacheDirLength 3<br />
91 </IfModule> <br />
93 # When acting as a proxy, don't cache the list of security updates<br />
94 CacheDisable http://security.update.server/update-list/<br />
100 <section id="thunderingherd"><title>Avoiding the Thundering Herd</title>
101 <p>When a cached entry becomes stale, <module>mod_cache</module> will submit
102 a conditional request to the backend, which is expected to confirm whether the
103 cached entry is still fresh, and send an updated entity if not.</p>
104 <p>A small but finite amount of time exists between the time the cached entity
105 becomes stale, and the time the stale entity is fully refreshed. On a busy
106 server, a significant number of requests might arrive during this time, and
107 cause a <strong>thundering herd</strong> of requests to strike the backend
108 suddenly and unpredicably.</p>
109 <p>To keep the thundering herd at bay, the <directive>CacheLock</directive>
110 directive can be used to define a directory in which locks are created for
111 URLs <strong>in flight</strong>. The lock is used as a <strong>hint</strong>
112 by other requests to either suppress an attempt to cache (someone else has
113 gone to fetch the entity), or to indicate that a stale entry is being refreshed
114 (stale content will be returned in the mean time).
117 <title>Initial caching of an entry</title>
118 <p>When an entity is cached for the first time, a lock will be created for the
119 entity until the response has been fully cached. During the lifetime of the
120 lock, the cache will suppress the second and subsequent attempt to cache the
121 same entity. While this doesn't hold back the thundering herd, it does stop
122 the cache attempting to cache the same entity multiple times simultaneously.
126 <title>Refreshment of a stale entry</title>
127 <p>When an entity reaches its freshness lifetime and becomes stale, a lock
128 will be created for the entity until the response has either been confirmed as
129 still fresh, or replaced by the backend. During the lifetime of the lock, the
130 second and subsequent incoming request will cause stale data to be returned,
131 and the thundering herd is kept at bay.</p>
134 <title>Locks and Cache-Control: no-cache</title>
135 <p>Locks are used as a <strong>hint only</strong> to enable the cache to be
136 more gentle on backend servers, however the lock can be overridden if necessary.
137 If the client sends a request with a Cache-Control header forcing a reload, any
138 lock that may be present will be ignored, and the client's request will be
139 honoured immediately and the cached entry refreshed.</p>
140 <p>As a further safety mechanism, locks have a configurable maximum age.
141 Once this age has been reached, the lock is removed, and a new request is
142 given the opportunity to create a new lock. This maximum age can be set using
143 the <directive>CacheLockMaxAge</directive> directive, and defaults to 5
148 <title>Example configuration</title>
149 <example><title>Enabling the cache lock</title>
151 # Enable the cache lock<br />
153 <IfModule mod_cache.c><br />
156 CacheLockPath /tmp/mod_cache-lock<br />
157 CacheLockMaxAge 5<br />
164 <section id="finecontrol"><title>Fine Control with the CACHE Filter</title>
165 <p>Under the default mode of cache operation, the cache runs as a quick handler,
166 short circuiting the majority of server processing and offering the highest
167 cache performance available.</p>
169 <p>In this mode, the cache <strong>bolts onto</strong> the front of the server,
170 acting as if a free standing RFC2616 caching proxy had been placed in front of
173 <p>While this mode offers the best performance, the administrator may find that
174 under certain circumstances they may want to perform further processing on the
175 request after the request is cached, such as to inject personalisation into the
176 cached page, or to apply authorisation restrictions to the content. Under these
177 circumstances, an administrator is often forced to place independent reverse
178 proxy servers either behind or in front of the caching server to achieve this.</p>
180 <p>To solve this problem the <directive module="mod_cache">CacheQuickHandler
181 </directive> directive can be set to <strong>off</strong>, and the server will
182 process all phases normally handled by a non cached request, including the
183 <strong>authentication and authorisation</strong> phases.</p>
185 <p>In addition, the administrator may optionally specify the <strong>precise point
186 within the filter chain</strong> where caching is to take place by adding the
187 <strong>CACHE</strong> filter to the output filter chain.</p>
189 <p>For example, to cache content before applying compression to the response,
190 place the <strong>CACHE</strong> filter before the <strong>DEFLATE</strong>
191 filter as in the example below:</p>
194 # Cache content before optional compression<br />
195 CacheQuickHandler off<br />
196 AddOutputFilterByType CACHE;DEFLATE text/plain<br /><br />
199 <p>Another option is to have content cached before personalisation is applied
200 by <module>mod_include</module> (or another content processing filter). In this
201 example templates containing tags understood by
202 <module>mod_include</module> are cached before being parsed:</p>
205 # Cache content before mod_include and mod_deflate<br />
206 CacheQuickHandler off<br />
207 AddOutputFilterByType CACHE;INCLUDES;DEFLATE text/html<br /><br />
210 <p>You may place the <strong>CACHE</strong> filter anywhere you wish within the
211 filter chain. In this example, content is cached after being parsed by
212 <module>mod_include</module>, but before being processed by
213 <module>mod_deflate</module>:</p>
216 # Cache content between mod_include and mod_deflate<br />
217 CacheQuickHandler off<br />
218 AddOutputFilterByType INCLUDES;CACHE;DEFLATE text/html<br /><br />
221 <note type="warning"><title>Warning:</title>If the location of the
222 <strong>CACHE</strong> filter in the filter chain is changed for any reason,
223 you may need to <strong>flush your cache</strong> to ensure that your data
224 served remains consistent. <module>mod_cache</module> is not in a position
225 to enforce this for you.</note>
230 <name>CacheEnable</name>
231 <description>Enable caching of specified URLs using a specified storage
232 manager</description>
233 <syntax>CacheEnable <var>cache_type</var> <var>url-string</var></syntax>
234 <contextlist><context>server config</context><context>virtual host</context>
238 <p>The <directive>CacheEnable</directive> directive instructs
239 <module>mod_cache</module> to cache urls at or below
240 <var>url-string</var>. The cache storage manager is specified with the
241 <var>cache_type</var> argument. If the <directive>CacheEnable</directive>
242 directive is placed inside a <directive type="section">Location</directive>
243 directive, the <var>url-string</var> becomes optional.
244 <var>cache_type</var> <code>disk</code> instructs
245 <module>mod_cache</module> to use the disk based storage manager
246 implemented by <module>mod_disk_cache</module>.</p>
247 <p>In the event that the URL space overlaps between different
248 <directive>CacheEnable</directive> directives (as in the example below),
249 each possible storage manager will be run until the first one that
250 actually processes the request. The order in which the storage managers are
251 run is determined by the order of the <directive>CacheEnable</directive>
252 directives in the configuration file.</p>
254 <p>When acting as a forward proxy server, <var>url-string</var> can
255 also be used to specify remote sites and proxy protocols which
256 caching should be enabled for.</p>
259 # Cache proxied url's<br />
260 CacheEnable disk /<br /><br />
261 # Cache FTP-proxied url's<br />
262 CacheEnable disk ftp://<br /><br />
263 # Cache content from www.apache.org<br />
264 CacheEnable disk http://www.apache.org/<br />
267 <p>A hostname starting with a <strong>"*"</strong> matches all hostnames with
268 that suffix. A hostname starting with <strong>"."</strong> matches all
269 hostnames containing the domain components that follow.</p>
272 # Match www.apache.org, and fooapache.org<br />
273 CacheEnable disk http://*apache.org/<br />
274 # Match www.apache.org, but not fooapache.org<br />
275 CacheEnable disk http://.apache.org/<br />
278 <p> The <code>no-cache</code> environment variable can be set to
279 disable caching on a finer grained set of resources in versions
280 2.2.12 and later.</p>
283 <seealso><a href="../env.html">Environment Variables in Apache</a></seealso>
287 <name>CacheDisable</name>
288 <description>Disable caching of specified URLs</description>
289 <syntax>CacheDisable <var>url-string</var> | <var>on</var></syntax>
290 <contextlist><context>server config</context><context>virtual host</context>
294 <p>The <directive>CacheDisable</directive> directive instructs
295 <module>mod_cache</module> to <em>not</em> cache urls at or below
296 <var>url-string</var>.</p>
298 <example><title>Example</title>
299 CacheDisable /local_files
302 <p>If used in a <directive type="section">Location</directive> directive,
303 the path needs to be specified below the Location, or if the word "on"
304 is used, caching for the whole location will be disabled.</p>
306 <example><title>Example</title>
307 <Location /foo><br />
308 CacheDisable on<br />
309 </Location><br />
312 <p> The <code>no-cache</code> environment variable can be set to
313 disable caching on a finer grained set of resources in versions
314 2.2.12 and later.</p>
317 <seealso><a href="../env.html">Environment Variables in Apache</a></seealso>
320 <name>CacheMaxExpire</name>
321 <description>The maximum time in seconds to cache a document</description>
322 <syntax>CacheMaxExpire <var>seconds</var></syntax>
323 <default>CacheMaxExpire 86400 (one day)</default>
324 <contextlist><context>server config</context><context>virtual host</context>
328 <p>The <directive>CacheMaxExpire</directive> directive specifies the maximum number of
329 seconds for which cachable HTTP documents will be retained without checking the origin
330 server. Thus, documents will be out of date at most this number of seconds. This maximum
331 value is enforced even if an expiry date was supplied with the document.</p>
334 CacheMaxExpire 604800
340 <name>CacheMinExpire</name>
341 <description>The minimum time in seconds to cache a document</description>
342 <syntax>CacheMinExpire <var>seconds</var></syntax>
343 <default>CacheMinExpire 0</default>
344 <contextlist><context>server config</context><context>virtual host</context>
348 <p>The <directive>CacheMinExpire</directive> directive specifies the minimum number of
349 seconds for which cachable HTTP documents will be retained without checking the origin
350 server. This is only used if no valid expire time was supplied with the document.</p>
360 <name>CacheDefaultExpire</name>
361 <description>The default duration to cache a document when no expiry date is specified.</description>
362 <syntax>CacheDefaultExpire <var>seconds</var></syntax>
363 <default>CacheDefaultExpire 3600 (one hour)</default>
364 <contextlist><context>server config</context><context>virtual host</context>
368 <p>The <directive>CacheDefaultExpire</directive> directive specifies a default time,
369 in seconds, to cache a document if neither an expiry date nor last-modified date are provided
370 with the document. The value specified with the <directive>CacheMaxExpire</directive>
371 directive does <em>not</em> override this setting.</p>
374 CacheDefaultExpire 86400
380 <name>CacheIgnoreNoLastMod</name>
381 <description>Ignore the fact that a response has no Last Modified
382 header.</description>
383 <syntax>CacheIgnoreNoLastMod On|Off</syntax>
384 <default>CacheIgnoreNoLastMod Off</default>
385 <contextlist><context>server config</context><context>virtual host</context>
389 <p>Ordinarily, documents without a last-modified date are not cached.
390 Under some circumstances the last-modified date is removed (during
391 <module>mod_include</module> processing for example) or not provided
392 at all. The <directive>CacheIgnoreNoLastMod</directive> directive
393 provides a way to specify that documents without last-modified dates
394 should be considered for caching, even without a last-modified date.
395 If neither a last-modified date nor an expiry date are provided with
396 the document then the value specified by the
397 <directive>CacheDefaultExpire</directive> directive will be used to
398 generate an expiration date.</p>
401 CacheIgnoreNoLastMod On
407 <name>CacheIgnoreCacheControl</name>
408 <description>Ignore request to not serve cached content to client</description>
409 <syntax>CacheIgnoreCacheControl On|Off</syntax>
410 <default>CacheIgnoreCacheControl Off</default>
411 <contextlist><context>server config</context><context>virtual host</context>
415 <p>Ordinarily, requests containing a Cache-Control: no-cache or
416 Pragma: no-cache header value will not be served from the cache. The
417 <directive>CacheIgnoreCacheControl</directive> directive allows this
418 behavior to be overridden. <directive>CacheIgnoreCacheControl On</directive>
419 tells the server to attempt to serve the resource from the cache even
420 if the request contains no-cache header values. Resources requiring
421 authorization will <em>never</em> be cached.</p>
424 CacheIgnoreCacheControl On
427 <note type="warning"><title>Warning:</title>
428 This directive will allow serving from the cache even if the client has
429 requested that the document not be served from the cache. This might
430 result in stale content being served.
433 <seealso><directive module="mod_cache">CacheStorePrivate</directive></seealso>
434 <seealso><directive module="mod_cache">CacheStoreNoStore</directive></seealso>
438 <name>CacheIgnoreQueryString</name>
439 <description>Ignore query string when caching</description>
440 <syntax>CacheIgnoreQueryString On|Off</syntax>
441 <default>CacheIgnoreQueryString Off</default>
442 <contextlist><context>server config</context><context>virtual host</context>
446 <p>Ordinarily, requests with query string parameters are cached separately
447 for each unique query string. This is according to RFC 2616/13.9 done only
448 if an expiration time is specified. The
449 <directive>CacheIgnoreQueryString</directive> directive tells the cache to
450 cache requests even if no expiration time is specified, and to reply with
451 a cached reply even if the query string differs. From a caching point of
452 view the request is treated as if having no query string when this
453 directive is enabled.</p>
456 CacheIgnoreQueryString On
463 <name>CacheLastModifiedFactor</name>
464 <description>The factor used to compute an expiry date based on the
465 LastModified date.</description>
466 <syntax>CacheLastModifiedFactor <var>float</var></syntax>
467 <default>CacheLastModifiedFactor 0.1</default>
468 <contextlist><context>server config</context><context>virtual host</context>
472 <p>In the event that a document does not provide an expiry date but does
473 provide a last-modified date, an expiry date can be calculated based on
474 the time since the document was last modified. The
475 <directive>CacheLastModifiedFactor</directive> directive specifies a
476 <var>factor</var> to be used in the generation of this expiry date
477 according to the following formula:
479 <code>expiry-period = time-since-last-modified-date * <var>factor</var>
480 expiry-date = current-date + expiry-period</code>
482 For example, if the document was last modified 10 hours ago, and
483 <var>factor</var> is 0.1 then the expiry-period will be set to
484 10*0.1 = 1 hour. If the current time was 3:00pm then the computed
485 expiry-date would be 3:00pm + 1hour = 4:00pm.
487 If the expiry-period would be longer than that set by
488 <directive>CacheMaxExpire</directive>, then the latter takes
492 CacheLastModifiedFactor 0.5
498 <name>CacheIgnoreHeaders</name>
499 <description>Do not store the given HTTP header(s) in the cache.
501 <syntax>CacheIgnoreHeaders <var>header-string</var> [<var>header-string</var>] ...</syntax>
502 <default>CacheIgnoreHeaders None</default>
503 <contextlist><context>server config</context><context>virtual host</context>
507 <p>According to RFC 2616, hop-by-hop HTTP headers are not stored in
508 the cache. The following HTTP headers are hop-by-hop headers and thus
509 do not get stored in the cache in <em>any</em> case regardless of the
510 setting of <directive>CacheIgnoreHeaders</directive>:</p>
513 <li><code>Connection</code></li>
514 <li><code>Keep-Alive</code></li>
515 <li><code>Proxy-Authenticate</code></li>
516 <li><code>Proxy-Authorization</code></li>
517 <li><code>TE</code></li>
518 <li><code>Trailers</code></li>
519 <li><code>Transfer-Encoding</code></li>
520 <li><code>Upgrade</code></li>
523 <p><directive>CacheIgnoreHeaders</directive> specifies additional HTTP
524 headers that should not to be stored in the cache. For example, it makes
525 sense in some cases to prevent cookies from being stored in the cache.</p>
527 <p><directive>CacheIgnoreHeaders</directive> takes a space separated list
528 of HTTP headers that should not be stored in the cache. If only hop-by-hop
529 headers not should be stored in the cache (the RFC 2616 compliant
530 behaviour), <directive>CacheIgnoreHeaders</directive> can be set to
531 <code>None</code>.</p>
533 <example><title>Example 1</title>
534 CacheIgnoreHeaders Set-Cookie
537 <example><title>Example 2</title>
538 CacheIgnoreHeaders None
541 <note type="warning"><title>Warning:</title>
542 If headers like <code>Expires</code> which are needed for proper cache
543 management are not stored due to a
544 <directive>CacheIgnoreHeaders</directive> setting, the behaviour of
545 mod_cache is undefined.
551 <name>CacheIgnoreURLSessionIdentifiers</name>
552 <description>Ignore defined session identifiers encoded in the URL when caching
554 <syntax>CacheIgnoreURLSessionIdentifiers <var>identifier</var> [<var>identifier</var>] ...</syntax>
555 <default>CacheIgnoreURLSessionIdentifiers None</default>
556 <contextlist><context>server config</context><context>virtual host</context>
560 <p>Sometimes applications encode the session identifier into the URL like in the following
564 <li><code>/someapplication/image.gif;jsessionid=123456789</code></li>
565 <li><code>/someapplication/image.gif?PHPSESSIONID=12345678</code></li>
567 <p>This causes cachable resources to be stored separately for each session, which
568 is often not desired. <directive>CacheIgnoreURLSessionIdentifiers</directive> lets
569 define a list of identifiers that are removed from the key that is used to identify
570 an entity in the cache, such that cachable resources are not stored separately for
573 <p><code>CacheIgnoreURLSessionIdentifiers None</code> clears the list of ignored
574 identifiers. Otherwise, each identifier is added to the list.</p>
576 <example><title>Example 1</title>
577 CacheIgnoreURLSessionIdentifiers jsessionid
580 <example><title>Example 2</title>
581 CacheIgnoreURLSessionIdentifiers None
588 <name>CacheStorePrivate</name>
589 <description>Attempt to cache responses that the server has marked as private</description>
590 <syntax>CacheStorePrivate On|Off</syntax>
591 <default>CacheStorePrivate Off</default>
592 <contextlist><context>server config</context><context>virtual host</context>
596 <p>Ordinarily, responses with Cache-Control: private header values will not
597 be stored in the cache. The <directive>CacheStorePrivate</directive>
598 directive allows this behavior to be overridden.
599 <directive>CacheStorePrivate</directive> On
600 tells the server to attempt to cache the resource even if it contains
601 private header values. Resources requiring authorization will
602 <em>never</em> be cached.</p>
608 <note type="warning"><title>Warning:</title>
609 This directive will allow caching even if the upstream server has
610 requested that the resource not be cached. This directive is only
611 ideal for a 'private' cache.
614 <seealso><directive module="mod_cache">CacheIgnoreCacheControl</directive></seealso>
615 <seealso><directive module="mod_cache">CacheStoreNoStore</directive></seealso>
619 <name>CacheStoreNoStore</name>
620 <description>Attempt to cache requests or responses that have been marked as no-store.</description>
621 <syntax>CacheStoreNoStore On|Off</syntax>
622 <default>CacheStoreNoStore Off</default>
623 <contextlist><context>server config</context><context>virtual host</context>
627 <p>Ordinarily, requests or responses with Cache-Control: no-store header
628 values will not be stored in the cache. The
629 <directive>CacheStoreNoCache</directive> directive allows this
630 behavior to be overridden. <directive>CacheStoreNoCache</directive> On
631 tells the server to attempt to cache the resource even if it contains
632 no-store header values. Resources requiring authorization will
633 <em>never</em> be cached.</p>
639 <note type="warning"><title>Warning:</title>
640 As described in RFC 2616, the no-store directive is intended to
641 "prevent the inadvertent release or retention of sensitive information
642 (for example, on backup tapes)." Enabling this option could store
643 sensitive information in the cache. You are hereby warned.
646 <seealso><directive module="mod_cache">CacheIgnoreCacheControl</directive></seealso>
647 <seealso><directive module="mod_cache">CacheStorePrivate</directive></seealso>
651 <name>CacheLock</name>
652 <description>Enable the thundering herd lock.</description>
653 <syntax>CacheLock <var>on|off</var></syntax>
654 <default>CacheLock off</default>
655 <contextlist><context>server config</context><context>virtual host</context>
659 <p>The <directive>CacheLock</directive> directive enables the thundering herd lock
660 for the given URL space.</p>
662 <p>In a minimal configuration the following directive is all that is needed to
663 enable the thundering herd lock in the default system temp directory.</p>
666 # Enable cache lock<br />
667 CacheLock on<br /><br />
674 <name>CacheLockPath</name>
675 <description>Set the lock path directory.</description>
676 <syntax>CacheLockPath <var>directory</var></syntax>
677 <default>CacheLockPath /tmp/mod_cache-lock</default>
678 <contextlist><context>server config</context><context>virtual host</context>
682 <p>The <directive>CacheLockPath</directive> directive allows you to specify the
683 directory in which the locks are created. By default, the system's temporary
684 folder is used. Locks consist of empty files that only exist for stale URLs
685 in flight, so is significantly less resource intensive than the traditional
692 <name>CacheLockMaxAge</name>
693 <description>Set the maximum possible age of a cache lock.</description>
694 <syntax>CacheLockMaxAge <var>integer</var></syntax>
695 <default>CacheLockMaxAge 5</default>
696 <contextlist><context>server config</context><context>virtual host</context>
700 <p>The <directive>CacheLockMaxAge</directive> directive specifies the maximum
701 age of any cache lock.</p>
703 <p>A lock older than this value in seconds will be ignored, and the next
704 incoming request will be given the opportunity to re-establish the lock.
705 This mechanism prevents a slow client taking an excessively long time to refresh
712 <name>CacheQuickHandler</name>
713 <description>Run the cache from the quick handler.</description>
714 <syntax>CacheQuickHandler <var>on|off</var></syntax>
715 <default>CacheQuickHandler on</default>
716 <contextlist><context>server config</context><context>virtual host</context>
720 <p>The <directive module="mod_cache">CacheQuickHandler</directive> directive
721 controls the phase in which the cache is handled.</p>
723 <p>In the default enabled configuration, the cache operates within the quick
724 handler phase. This phase short circuits the majority of server processing,
725 and represents the most performant mode of operation for a typical server.
726 The cache <strong>bolts onto</strong> the front of the server, and the
727 majority of server processing is avoided.</p>
729 <p>When disabled, the cache operates as a normal handler, and is subject to
730 the full set of phases when handling a server request. While this mode is
731 slower than the default, it allows the cache to be used in cases where full
732 processing is required, such as when content is subject to authorisation.</p>
735 # Run cache as a normal handler<br />
736 CacheQuickHandler off<br /><br />
739 <p>It is also possible, when the quick handler is disabled, for the
740 administrator to choose the precise location within the filter chain where
741 caching is to be performed, by adding the <strong>CACHE</strong> filter to
745 # Cache content before mod_include and mod_deflate<br />
746 CacheQuickHandler off<br />
747 AddOutputFilterByType CACHE;INCLUDES;DEFLATE text/html<br /><br />
750 <p>If the CACHE filter is specified more than once, the last instance will