unbound en résolveur cache DNS local
Beaucoup (trop) de domaines ont un TTL absurdement faible (entre 0 et 5 minutes), ce qui provoque - au bout de ce TTL - à nouveaux des requêtes DNS sortantes. Autrement dit: Beaucoup de requêtes DNS sortantes pour rien, qui ajoutent un délai de traitement inutile (surtout quand les DNS de votre FAI sont lents ou que votre connexion n'est pas très rapide).

Ubound est un résolveur DNS. On peut s'en servir comme résolveur pour un réseau local, mais dans cette page on ne va l'aborder que dans le cadre d'un résolveur utilisé uniquement par la machine sur laquelle il est installé. L'objectif est d'améliorer les temps de réponse des requêtes DNS des applications en utilisant le cache d'unbound.

Cette page contient donc les instructions pour installer un unbound local en forçant le TTL à 24 heures.

Resolver for Home Networks
In this tutorial we’ll look at setting up Unbound as a DNS resolver; First for your own machine, and then for your entire network.
https://unbound.docs.nlnetlabs.nl/en/latest/use-cases/home-resolver.html

TEST
sudo watch "unbound-control stats_noreset | grep -F total.num.cache"
sudo unbound-control stats_noreset | grep -F total.num.cache

Like any other operating system, GNU/Linux has implemented memory management efficiently and even more than that. However, if any process is eating away your memory and you want to clear it, Linux provides a way to flush or clear the RAM cache.

How to Clear the DNS Cache on Linux

We can use the resolvectl command with the statistics option to see how many records are in the cache.

resolvectl statistics

Flushing the cache removes all entries, and starts the collection process once more. If there are any, this forcibly removes incorrect and corrupt entries from the cache.

The command is simple; we use resolvectl with the flush-caches option.

resolvectl flush-caches

We're silently returned to the command line. To confirm that something has actually happened, we'll check the DNS cache statistics again.

resolvectl statistics

To make your Mac, iPhone, or iPad run faster, you can clear Safari's cache. While you're at it, you can clear its history and cookies as well."

Vider son cache DNS en ligne de commande.

Maintenant pour les utilisateurs avancés, ou pour ceux qui ne veulent pas installer de logiciels supplémentaires, voici la même chose mais en ligne de commande. Ce tutoriel est basé sur MAC OS High Sierra 10.13.1.

Ouvrer un Terminal puis taper la commande suivante (OS X 10.12 et suivante) :

sudo killall -HUP mDNSResponder;sudo killall mDNSResponderHelper;sudo dscacheutil -flushcache

Image-Clean DNS cache

Videocacheview is a free utility tool that allows you to extract video files from the cache of your web browser. When you watch a video on the internet, it gets saved in the cache of your browser so that it can be loaded quickly the next time you visit the same website. Videocacheview can scan the cache of your web browser and extract the video files that have been saved, allowing you to save them to your local disk and watch them offline.

To use Videocacheview, you simply need to download and run the program. It will automatically detect the web browsers installed on your system and display a list of all the video files that have been saved in their cache. You can then select the videos you want to extract and save them to a folder on your computer.

Videocacheview supports various web browsers such as Internet Explorer, Firefox, Chrome, and Opera, and it can extract a wide range of video file formats, including FLV, MP4, WebM, and more. However, it's worth noting that using Videocacheview to extract copyrighted videos may be illegal, so you should only use this tool for personal use or with videos that you have the legal right to download.

How to Flush the DNS Cache in Ubuntu and Linux? Execute this command to Flush DNS cache on your Ubuntu and Linux Mint systems.
sudo /etc/init.d/dns-clean start

How to Flush DNS Cache on a Mac
https://www.lifewire.com/flush-dns-cache-on-a-mac-5209298

Disable Local DNS Caching on Ubuntu and LinuxMint
https://tecadmin.net/disable-local-dns-caching-ubuntu/

Flush DNS Cache on Windows and MacOS
https://tecadmin.net/clear-dns-cache-windows/

You can flush the DNS on your Mac by entering a command into the Terminal, which you can access via Spotlight or Utilities.

 How to Clear DNS Cache in MacOS Ventura & MacOS Monterey