Editing Web server (section)

===Anti-overload techniques===
To partially overcome above average load limits and to prevent overload, most popular websites use common techniques like the following ones (e.g.).
* Tuning OS parameters for hardware capabilities and usage.
* Tuning web server(s) parameters to improve their security and performances.
* Deploying {{strong|[[web cache]]}} techniques (not only for static contents but, whenever possible, for dynamic contents too).
* Managing network traffic, by using:
** [[Firewall (computing)|Firewall]]s to block unwanted traffic coming from bad IP sources or having bad patterns;
** HTTP traffic managers to drop, redirect or rewrite requests having bad [[HTTP]] patterns;
** [[Bandwidth management]] and [[traffic shaping]], in order to smooth down peaks in network usage.
* Using different [[domain name]]s, [[IP address]]es and computers to serve different kinds (static and dynamic) of content; the aim is to '''separate''' big or huge files (<code>download.*</code>) (that domain might be replaced also by a [[Content delivery network|CDN]]) from small and medium-sized files (<code>static.*</code>) and from main dynamic site (maybe where some contents are stored in a [[Back-end database|backend database]]) (<code>www.*</code>); the idea is to be able to efficiently serve big or huge (over 10 – 1000 MB) files (maybe throttling downloads) and to fully [[web cache|cache]] small and medium-sized files, without affecting performances of dynamic site under heavy load, by using different settings for each (group) of web server computers, e.g.:
** <code><nowiki>https://download.example.com</nowiki></code>
** <code><nowiki>https://static.example.com</nowiki></code>
** <code><nowiki>https://www.example.com</nowiki></code>
* Using many web servers (computers) that are grouped together behind a [[Load balancing (computing)|load balancer]] so that they act or are seen as one big web server.
* Adding more hardware resources (i.e. [[random-access memory|RAM]], fast [[Disk storage|disks]]) to each computer.
* Using more efficient computer programs for web servers (see also: [[#Software efficiency|software efficiency]]).
* Using the most efficient {{strong|[[#StandardCGIs|Web Server Gateway Interface]]}} to process dynamic requests (spawning one or more external programs every time a dynamic page is retrieved, kills performances).
* Using other programming techniques and [[workaround]]s, especially if dynamic content is involved, to speed up the HTTP responses (i.e. by avoiding dynamic calls to retrieve objects, such as style sheets, images and scripts), that never change or change very rarely, by copying that content to static files once and then keeping them synchronized with dynamic content).
* Using latest efficient versions of [[Hypertext Transfer Protocol|HTTP]] (e.g. beyond using common HTTP/1.1 also by enabling [[HTTP/2]] and maybe [[HTTP/3]] too, whenever available web server software has reliable support for the latter two protocols) in order to reduce a lot the number of TCP/IP connections started by each client and the size of data exchanged (because of more compact HTTP headers representation and maybe data compression). This may not prevent overloads of RAM and CPU caused by the need for encryption. It may also not address overloads caused by excessively large files uploaded at high speed, because they are optimized for concurrency.<ref name="nextcloud-http2-slow-upload">{{Cite web|url=https://github.com/nextcloud/server/issues/25297|title=Slow uploads with HTTP/2|author=many|publisher=github|date=2021-01-24|access-date=2021-11-15|language=en|archive-date=16 November 2021|archive-url=https://web.archive.org/web/20211116002101/https://github.com/nextcloud/server/issues/25297|url-status=live}}</ref><ref name="nginx-http2-slow-upload">{{Cite web|url=https://blog.cloudflare.com/delivering-http-2-upload-speed-improvements/|title=Delivering HTTP/2 upload speed improvements|author=Junho Choi|publisher=Cloudflare|date=2020-08-24|access-date=2021-11-15|language=en|archive-date=16 November 2021|archive-url=https://web.archive.org/web/20211116002101/https://blog.cloudflare.com/delivering-http-2-upload-speed-improvements/|url-status=live}}</ref>