The Basics of 301 Redirect Every SEO Specialist Should Know


When operating a website, it’s common to undergo domain transfers or URL changes, necessitating the use of 301 redirect in many cases. Failure to set them up properly can lead to a decrease in search traffic, so it’s crucial to understand and utilize them correctly.

What is 301 redirect?

301 redirect refers to an HTTP status code that signifies that a URL has permanently been transferred.
When a client (web browser) sends a request to a web server, the web server returns a response. The HTTP status code refers to the results of executing the request contained in the response.

(Figure 1: The communication between the client and the web server)

For URLs with 301 redirect, when a request is sent, it is redirected on the web server and the new URL is returned as a response.

(Figure 2: The HTML files and execution results are returned in the HTTP response)

When accessing a URL with a 301 redirect set up, there is the aforementioned exchange between the user’s browser and the web server. However, unless users are careful to check the address bar or inspect developer tools each time, they typically don’t notice the redirect.

The significance of 301 redirect in SEO

When you set up a 301 redirect, search engines recognize and process it as follows. When you want to change the URL of a web page to gain traffic from searches (to index it), setting up a 301 redirect is highly recommended.

— The difference between 301 redirect and 302 redirect

Users are redirected similarly to 301 redirect, but search engines understand them differently. Summarizing the differences from 301 redirect, they are as follows:

Google’s John Mueller has stated (29:22 on the source video below) that while 302 redirect communicate a temporary change to search engines, leaving them in place for an extended period may result in them being treated equivalently to 301 redirect. It’s important to be mindful of this aspect as well.

Source: English Google Webmaster Central office-hours hangout – YouTube

Main use cases of 301 redirect

The main use cases include the following patterns.

— Domain migration with domain change

With website transfers that encompass domain changes like the example shown below, transferring users from the old URL to the new URL will, in principle, require a 302 redirect for all URLs.When conducting a website transfer involving domain changes as shown below, where you want people who request the old URL to be redirected to the new URL, it’s generally necessary to use 301 redirect for all URLs.

— URL change of web pages

Even when changing URL rules instead of domains, as in such cases, 301 redirect is still set up.

— Normalize URLs

It’s recommended to choose one canonical version of a web page that contains the same content, especially when multiple URLs are accessible due to differences like the presence or absence of “www” or file extensions. Keeping the visited URL unified for users is advisable.

How to handle 301 redirect

When changing URLs, other actions besides setting up 301 redirect may also be necessary.

— Configuring 301 redirect

As stated in Google’s documentation, the specific setup method varies depending on the environment. Set it up according to your company’s website using the following page as a reference.

Source: Redirects and Google Search

— Other points to consider

When changing URLs, setting up redirects alone is not sufficient. Let’s reassess the need for changes in the following areas as well.

— Internal links and canonical destinations

If there are old URL destinations, update to the new URL to enable users and search engines to seamlessly access the new URL.

— sitemap.xml URLs

Immediately after setting up redirects, having search engines crawl both the old and new URLs can prompt detection of the redirects. Let’s notify the new URL via sitemap.xml. Once the index count of the old URL approaches zero, there’s no need to continue notifying the old URL.

— Descriptions on robots.txt

Let’s make sure that the current robots.txt configuration doesn’t affect the old and new URLs being targeted for changes. If crawling is not allowed for both, it might hinder the proper detection and crawling of redirects, potentially affecting search traffic adversely.

Points to consider when setting up a 301 redirect

Let’s cover a few points of consider regarding 301 redirects.

— Avoid creating redirect chains

A redirect chain refers to a situation where multiple redirects occur sequentially. While Googlebot and browsers can follow multiple redirects, it’s preferable to avoid them because they can increase user wait times and some browsers may not handle long redirect chains well. Google’s documentation suggests keeping redirect chains under 5 redirects (ideally 3 or fewer). If you find yourself in a situation where a redirect chain is unavoidable, aim to keep the number of redirects within this recommended range.

Source: How to move a site

— Set up redirects appropriately when changing URLs (there will still be cases in which traffic will decrease)

When changing URLs, it’s recommended to set up appropriate redirects to indicate the relationship between the old and new URLs to search engines. Without redirects, the new URL will be evaluated from scratch by search engines, potentially taking a long time to regain the search traffic previously acquired by the old URL (and sometimes never fully recovering).

Even when redirects are set up properly (especially in cases involving domain changes), it may take some time for the evaluation of the old URL to be transferred to the new URL. During this period, there might be a decrease in traffic, so it’s important to be aware of this possibility.

— Set up 301 redirect to remain in place for as long as possible (at least for a minimum of one year)

Avoid removing redirects immediately even if the destination URL has been indexed. This is because removing redirects can prevent users, especially those following external links not under the control of site operators, from being directed to the website. When URLs are changed, it’s recommended to keep the redirects in place for as long as possible. From the perspective of search engine processing, it’s suggested to maintain redirects for a minimum of one year.

Source: How long to keep 301 redirects? #AskGooglebot – YouTube

Types of redirects

It’s useful to recognize that there are various types of redirect methods. Redirects implemented on the server-side are more easily recognized by search engines.

— Server-side redirect

This method, implemented on the server-side, is the most recommended when changing URLs you want to index. The 301 redirect explained in this article falls under this category.

— Redirect using the meta refresh tag

If server-side redirects are difficult, an alternative method is to use the meta tag. You can place a meta refresh tag in the HTML head section or along with server-side code in HTTP headers.

— Redirect using JavaScript

When implementing server-side redirects or using the meta refresh tag is challenging, JavaScript redirection can be an alternative method. Redirects are carried out through JavaScript execution, but it’s important to note that it’s not certain whether Googlebot can detect these redirects reliably. (Googlebot tries to render after crawling, but it may fail.)

*Rendering refers to generating the screen that users view based on files like HTML, including executing JavaScript.
*Source: Redirects and Google Search


This article explained other necessary actions required when setting up a 301 redirect. When making changes to URLs, such as migrating a website, setting up redirects is crucial to avoid a decrease in organic search traffic. If you’re considering a website migration involving URL changes, we can assist you with migration considerations that take search engines into account. Please feel free to reach out to us for further assistance.

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