cache – nginx, http ddos protection crawled?

What is the best way to prevent crawlers from caching the “javascript verification” page?

With Google there are no problems, but Bing does seem to cache it. All it takes – for the bot – is to reload the page.

Whitelisting crawler IPs seems like boring and not so good solution to me.

I’ve added those headers to my nginx config “add_header Cache-Control “max-age=0, no-store, no-cache, must-revalidate”;” Do you think will it help?

The protection is lua based in-case it’s important information. Thank you.

what is cache keyword in analytics?

When I am check google analytics, I see some keywords like “cache:2933b974en0J:”.
My question is that why is this showing in google analytics??
what is the problem? how can I solve it?
enter image description here

cache – Can baking EMMC chip revive a dead motherboard?

I think my phones EMMC chip is dead.
At my days i baked some dead graphic cards and get somewhat good results.

Can same thing work with EMMC chip on a phone?

If you never heard of it here a link.

My original problem here if you are curious.Asus zenfone 6 E:failed to mount/ cache

samsung – Is it safe to manually “clear cache” of apps on Android?

Ever since I updated Device Care on my Samsung Galaxy A10s running Android Pie, I lost my “Clear Space” option that clears unnecessary data, including cache of all apps including system apps on my phone!

Since, I’m not installing any third party apps, for this purpose, I decided to manually “clear cache” of any desired apps from Settings > Apps > App name and tapping Clear Cache. To my surprise, I found the Gallery app has about half a GB of cache, and I immediately cleared it.

I realize that apps cache stuff to improve performance, predict data to auto fill on text boxes, and various other stuff, to improve user experience. But that’s taking up a lot of my Internal memory!

My question is :

  • Is this a safe practice?

  • Will this procedure damage the executable or normal functioning of my app?

  • Or, whether all these are dependent on the App developer / manufacturer ?

  • For default apps like Gallery or Chrome is this a safe practice?

apache 2.4 – Does mod_pagespeed PURGE downstream when its cache purges?

Does google mod_pagespeed send PURGE requests to configured downstream reverse proxies when an item in the mod_pagespeed cache is purged?

I’m running Debian 10 with varnish 6 (a varnish 4.0 vcl) sitting downstream from apache2 with google’s mod_pagespeed apache module. There’s also an nginx reverse proxy downstream of those for https termination, but that shouldn’t be relevant.

Apache Server w/ mod_pagespeed <--> Varnish <--> Nginx <--> (Internet) <--> User Agent

At the time of writing, the official mod_pagespeed documentation that describes how to configure a downstream reverse proxy (ModPagespeedDownstreamCachePurgeLocationPrefix) like Varnish Cache describes how it will send a PURGE request to your configured downstream when a more-optimized version is available at the backend (ie: when an optimized image has finished being written to disk:

To support downstream caching PageSpeed sends a purge request to the
caching layer whenever it identifies an opportunity for more rewriting
to be done on content that was just served. Such opportunities could
arise because of, say, the resources now becoming available in the
PageSpeed cache or an image compression operation completing. The
cache purge forces the next request for the HTML file to come all the
way to the backend PageSpeed server and obtain better rewritten
content, which is then stored in the cache.


However, surprisingly, the PageSpeed documentation does not mention anything about sending PURGE requests to the downstream cache whenever that optimized content suddenly becomes unavailable, such as when the PageSpeed cache is filled (utilizing >= ModPagespeedFileCacheSizeKb) and the optimized content (which may be referenced by one or many html files cached by varnish) is purged from the backend PageSpeed cache after the cache clean interval (ModPagespeedFileCacheCleanIntervalMs).

If an item is about to be purged from PageSpeed’s cache, will mod_pagespeed first send a PURGE request to the downstream cache?

Virtual Memory vs Cache for block identification

Both are based on the principle of locality. Then why virtual memory uses table lookup while cache memory uses associative memory for block identification?

cache – What do I do if my WordPress site is suddenly sanitizing portions of URLs it shouldn’t?

Nobody has touched wp-admin for this site in weeks. Suddenly, URLs are being sanitized in ways that break everything. The question marks of query parameters are being replaced with URL escape code %3F, which is obviously breaking nearly every script and stylesheet include that’s affected. The result is content like this:

<script type='text/javascript' src=""></script>

<script type='text/javascript' src='wp-includes/js/wp-embed.min.js%3Fver=5.4.1'></script>

Some, but not all URLs in the document are affected. Scripts and some anchor elements are affected.

In addition to this URL madness, it seems like portions of the main site are being included in every single page – i.e., the homepage’s markup is being embedded within wp-admin pages, etc.

The effect is that the site can essentially not be used – large dynamic portions of pages, especially the main landing page, simply fail to load or appear malformed due to missing scripts and stylesheets.

I should add that it’s nearly impossible to navigate wp-admin given the absurd state that it’s in at the moment, so I can’t really find my way around to do regular diagnostics.

How do I even begin to fix something like this? If this wasn’t a moneymaking site with plenty of content I haven’t even touched (‘the last guy’ decided to install dozens of plugins whose purposes are difficult to decipher, are possibly redundant, and might break everything if removed) I would gladly just reinstall everything.

I have attempted:

  • Removing a “WP Fastest Cache” plugin which, according to some, ‘breaks everything’ as of this month. Edit: It looks like this plugin is parasitic. After deactivating it, clearing my local cache, etc., pages still contain a comment marking them as having been cached by it…

  • Visiting and re-saving permalink settings in wp-admin as suggested by a comment I found in a similar issue elsewhere.

boot loop – Asus zenfone 6 E: mount / cache failure

The phone hangs when loading the startup.

clear data / factory reset gives
E: mount failure / caching error

clear cache partition
also fails.

abd sideload also give
E: mounting / cache failure
Unable to open vs ..

Many of the same articles suggest TWRP but I don't have it. Didn't understand how to install it on a phone can not open.

Many others say that the EMMC chip is dead. I hope not. I know it is very likely but I want to try other options first if I can.

cache – Farm not available after installing Language Pack

I’m a beginner in Sharepoint world.

I had a working farm and I decided to install a Language Pack. I follow the instructions and:
– first time I did the installing procedure it gave me a mistake
– I decided to do it again: second time it was succesful

From then, my farm is not available and Sharepoint is “not working”

Meanwhile I checked the services, IIS is working…what else shall I check?
– in a try to connect to existing farm, it said “cachehostinfo is null”

Thank you very much! 🙂

Average access time in two level cache system

In a two-level cache system, the level one cache has a hit time of 1 ns (inside the CPU), hit rate of 90%, and a miss penalty of 20 ns. The level two cache has a hit rate of 95% and a miss penalty of 220 ns. What is the average memory access time?

What is a two-level cache system and how to calculate the time required? Since the hit time of level two cache is missing…