What Is A Mirror Site?

Date First Published: 24th November 2022

Topic: Web Design & Development

Subtopic: SEO

Article Type: Computer Terms & Definitions

Difficulty: Medium

Difficulty Level: 4/10

CONTENTS

Why Are Website Mirrored?
SEO

Learn more about what a mirror site is in this article.

A mirror site, also known as a mirrored site, is an identical copy of another website located under a different URL. The files on the web server have been copied to another web server so that the webpages are available from more than one place. Mirror sites are often used when one site receives too much traffic and becomes overloaded so that the files can continue to be served to visitors and are still available. The sites are usually located in different geographical regions than the original site to serve the populations of those areas. In order to reflect the content of the original site, mirror sites are often updated on a regular basis.

The owners of some mirror sites choose not to completely copy the contents of the upstream server they are mirroring due to technical limitations or only selecting a small amount of content relevant for their purpose, such as files written in a certain programming language. These types of websites are called partial mirrors or secondary mirrors.

Note:

Mirror sites are not used as much now as a lot of sites now use a CDN to distribute content. CDNs enable users to connect to a geographically closer data centre rather than wherever the web server of a website is located.

Why Are Websites Mirrored?

Websites can be mirrored for the following reasons:

To ensure that the website is available if the original site receives too much traffic and becomes overloaded.
To preserve a website that is going to be closed or discontinued.
To allow faster downloads of files from specific geographical areas.
To ensure that information is available to places where access may be unreliable or censored and bypass censorship.
To balance the load put on the servers by a large audience.
To preserve historical content.
To provide a realtime backup of the original site.
To boost online presence.

SEO

Setting up mirror sites with identical content can lead to SEO issues as it will be detected as duplicate content by search engine bots and may confuse them as to which identical pages should appear higher when pages come up for certain keywords. Mirrored pages are disliked by search engines and they will often crawl the original URL and ignore the others. Google states that it 'tries hard to index and show pages with unique information'. Website owners can specify the version of the website they need in the Google search results page through Google Search Console functionality or they can add the canonical tag to the original pages. It is important to tell search engines which version of the website is the main one.