The following is a reply I received from my Web host as to why issues are occurring with WP Super Cache.
I hope this helps:
Hello there!
Sorry for the delay in response. Support queues are higher than we’d like right now, but let’s cut to the chase:
WP Super Cache is active, configured to HostGator’s specifications, and working.
For some unknown reason, despite extensive investigation, WP Super Cache’s own testing system fails because it is unable to resolve its own domain. The plugin is not making a DNS request to identify where www.navycs.com goes. I’ve never seen this error before, and it would be too time-consuming to go into the plugin and pinpoint the code that seems to be problematic. If this is concerning to you, I would recommend that you contact the developer of the plugin with the information I mentioned in this email.
The probable explanation for why you received the “Served super cache file from PHP” header is that the page that you read the headers from was already cached. Flushing your browser cache and the WP Super Cache cache would force your site to resend the page, which should not have that header value anymore.
I hope this information has been helpful to you. Please don’t hesitate to follow up if you have any more questions or concerns.
Sincerely,
Nick L.
Linux Systems Administrator
HostGator.com, LLC
My result of the Cache Tester:
Couldn’t resolve host ‘www.navycs.com’
Cache Tester
Test your cached website by clicking the test button below.
Fetching http://www.navycs.com/blogs/ to prime cache: OK
Fetching first copy of http://www.navycs.com/blogs/: FAILED
Fetching second copy of http://www.navycs.com/blogs/: FAILED
One or more page requests failed:
The pages do not match! Timestamps differ or were not found!
My server header for a page in my blog:
HTTP/1.1 200 OK
Date: Tue, 06 Aug 2013 20:24:29 GMT
Server: Apache
X-Powered-By: PHP/5.3.27
Vary: Accept-Encoding,Cookie,User-Agent
Cache-Control: max-age=3, must-revalidate
WP-Super-Cache: Served supercache file from PHP
Content-Encoding: gzip
Content-Length: 5740
Keep-Alive: timeout=5, max=75
Connection: Keep-Alive
Content-Type: text/html; charset=UTF-8
I apologize for posting again, but while looking at both sites, http://inphotos.org/ and http://ocaoimh.ie — the sites Donncha contributes to according to the links in the admin portion of the plug-in — both return “WP-Super-Cache: Served supercache file from PHP” in the server header. I assume mod_rewrite is used as recommended on both of those blogs, but they both appear not to be serving pages as designed (according to the header). Are those sites returning the errors listed above as my site does? Am I missing something? Is there a bug, or am I the only one experiencing this issue? I would love to figure out how to get the mod_rewrite to work — Hostgator is at a loss, too.
Does anyone have mod_rewrite option of this plug-in working??