Notes from the Google Webmaster Hangouts on the 9th and 12th of August, 2016.
Site: Returns URLs from Redirected Domains
URLs from redirected domains may still show up for a site: search
Add Last Modified to Redirects in Sitemaps
When Redirecting URLs include them in a Sitemap with a last modified date set after the redirect was put in place, it will encourage them to be crawled more quickly.
A Broken URL Won't Break an HREFLANG cluster
If some of your hreflang URLs are broken, it won’t prevent the rest of the hreflang cluster from working.
Allow Googlebot to see AB Test
If running an AB test, make sure to treat Googlebot in the same way. If you use multiple URLs, ensure that both versions are crawlable but canonicalise to the main version.
Deprecated HTML Doesn't affect Rankings
If you’re using out of date or incompatible HTML, it won’t affect the rankings for the page.
Don't Prevent Embedded File caching
If you prevent JS, CSS and image caching, such as a nocache header tag, Google will need to keep requesting the files for rendering, which may slow down crawling of the site.
WWW Subdomain Should Not be "Parked"
If the www version of your domain is “parked”, it might affect the indexing of the other versions of your domain.
Same Queries Might Serve both Static and Fresh Content
John suggests that some queries need to include both static and fresh content, and that queries may change over time.
Put HREFLANG Tags Higher Up In The Head
Google ignores noindex in image file headers
Google ignores x-robots noindex tags in image file headers.
Set up Image Redirects when URLs Change
If you change image URLs, set up redirects to help them get picked up more quickly.