What is the difference between JavaScript and HTTP redirects?
John explained that, in general, Google strongly prefers server-side redirects (301 or 302 redirects, for example) to JavaScript redirects.
If you use JavaScript to generate the redirect, Google first has to render the Javascript and see what it does, and then see the redirect and follow it. If you can’t do a server-side redirect, you can still use JavaScript, but it just takes longer for Google to process. Using a meta-refresh redirect is another option but again, this will take longer as it needs to be figured out by Google.
Use log file analysis to understand which older 404 pages may benefit from redirects
When doing a website migration, it’s important to make sure that important external links are redirected so that users don’t land on a 404 and the link is lost. This could also be reflected in the search results over time. John mentioned that a difference may not be noticed after a time period of two years, but that if there are really strong external links pointing to a 404 or broken link, it would still be worthwhile to redirect these pages. He clarified that you can further analyze this by using log files to see which older 404 pages search engines are still regularly trying to access. This could be a sign that they should be redirected to something more useful.
Updating backlinks to a migrated domain helps with canonicalization
An attendee was talking about a website migration from domain A to domain B. They were setting up redirects, but asked whether the page authority and rankings would be negatively affected if there were many existing backlinks that point to domain A.
John replied that setting up redirects and using the Change of Address tool in Search Console will help Google understand the changes that have occurred during a site migration. However, he said that on a per-page basis they also try to look at canonicalization. When dealing with canonicalization on migrated domains, John said that redirects, internal links, and canonical tags play a role —- but external links also play a role. What could happen, if Google sees a lot of external links going to the old URL, is that they might index the old URL instead of the new one. This could be because they think the change might be temporary due to these linking signals. During site migrations, they recommend finding the larger websites linking to your previous domain and requesting that those backlinks are updated to make sure that they can align everything with the new domain.
Noindexing pages with geo IP redirection is not ideal
One user asked about the use of geo IP redirection in conjunction with noindex tags. The example was having separate pages targeted at users in multiple locations, but using noindex tags to ensure just one is indexed.
John raised the point that Google typically crawls from one location (mostly using a Californian IP address). If the IP address directs Google to one of the URLs you have set to noindex, it might result in those pages not being indexed full stop. This approach, therefore, isn’t recommended. Instead, you should focus on making location-specific content easier to find once the user has landed on the site.
Images should also be redirected during a website migration
John answered a question about organic search fluctuations after a site migration. As well as checking the page differences before and after in regards to aspects like internal linking, content or structure, it’s also important to consider embedded content like images.
If you don’t redirect your old image URLs, Google needs to reprocess them again and will find them again as new because they don’t have the connection between the old and the new URL ones. He clarified that it can have a big effect if you have a lot of image search traffic. It makes sense to set up those redirects even if you’ve moved over a month or so ago.
Internal URL changes can cause organic search fluctuations
A participant was seeing organic search fluctuations after a URL structure change on their website, despite adding 301 redirects. They asked if that is expected and how long the process should take. John responded that changing internal URLs means they have to almost reprocess the entire website and understand the context of all the pages on the website first, which can take a significant amount of time.
You are likely to see fluctuations in organic search for at least a month or longer if it’s a bigger change. Fluctuations can also occur if other changes have also happened at the same time, such as internal linking, content, or page structure updates which could have caused the pages to become weaker. If this is the case, John recommended reviewing the pages before and after to understand these differences and which things might need clearing up.
Crawl rate is not affected by a large number of 304 responses
A question was asked about whether a large number of 304 responses could affect crawling. John replied that if a 304 is encountered, it means that Googlebot could reuse that request and crawl something else on the website and that it would not affect the crawl budget. If most pages on a website return a 304, it wouldn’t mean that the crawl rate would be reduced, just that the focus would be on the pages of the website where they see updates happening.
There is no negative SEO effect from 302 redirects
A question was asked about whether 302 redirects pass link equity, or if there are any other issues which mean they should be avoided. John said there is no negative SEO effect from 302 redirects. He explained there is no hidden SEO benefit of one redirect type over the other, but they serve different purposes. With a 301 redirect, you want Google systems to pick up the destination page. With a 302, you want Google to keep the original URL as it is only a temporary change. If it’s purely about tracking the ranking of individual URLs, then a 301 will cause the destination page to be indexed and ranking, and a 302 will keep the original indexed and ranking.
Long-term 302 redirects are eventually treated as 301 redirects
If you have 302 redirects in the long term, eventually Google will treat them the same as 301 redirects. John mentioned that if implementing 301 redirects is an issue, then 302 redirects could be an option as they work the same as normal redirects and still pass PageRank.