Redirects
URL redirection is a process put in place to forward site visitors to an alternative page when the page they are looking to view is no longer live on the site. Redirects may be implemented for migration purposes, as well as for site re-architecture and when pages naturally expire. They can also be used to consolidate ranking signals. Our SEO Office Hours notes below cover the different redirection types and explore how Google understands these.
Further reading: The ABCs of HTTP Status Codes
Use ‘If Modified Since’ to Optimise Crawling for Large Sites
Using ‘If Modified Since’ 304 headers is a clever way to optimise crawling of a large website with a lot of updating pages.
Use Sitemaps for Redirect Discovery
If you want Google to see your redirected URLs, such as after a URL change, it’s OK to submit the old URLs in a Sitemap to help Google recrawl them more quickly
Use Pagination to Join Split Pages
If you want to split up a page into 2 different URLs, you can’t redirect or canonicalise from the old URL to both new URLs. You can choose one of the new pages as the main one, and link to the secondary page. And you can paginate the pages together.
Redirect Image, JavaScript & CSS URLs
When you redevelop or change your website platform, you should also redirect all your images, JavaScript and CSS files as well so the new URLs can be discovered more quickly.
301/404 Won’t Cause Ranking Problems
Large numbers of 301 redirects and expired/low value URLs which 404 won’t directly cause any general ranking problems for the site (assuming you’re doing them properly and not losing important pages). But try to avoid chains of mutliple redirects.
Verify HTTP and HTTPS in Search Console to Migrate
If you migrate from HTTP to HTTPS, you need to have both verified in Webmaster Tools and set up a redirect, but you don’t need to use the change of address tool which is only for moving between different domains.
Avoid Redirect Chains
If you change domain and URL at the same time, you can have 2 redirects in a chain, although redirecting directly is preferred. Google can follow more than 5 redirects in a chain, but in separate crawling attempts.
Disavow Backlinks on New and Migrating Domains
If you migrate a site to a new domain which has unnatural backlinks, you should disavow the unnatural links on the new domain as well.
Use Disallow to Improve Crawling Efficiency
John recommends against robots.txt, because it prevents Google consolidating authority signals, but then says there are occassions when crawling efficiency is more important.
301 Redirects Pass Full PageRank on a Site Level but Not per URL
If you redirect a full domain, e.g. www to non-www, or http to https, the full authority will be passed over, but individual 301 redirects do not pass the full authority.