Google’s John Mueller answered a question about hosting images on separate sub-domains and whether it would help improve Google crawling on large websites.
The question refers to John’s statement during a past event; this time, his answer clarified that splitting image or content load makes sense if Google can’t efficiently crawl your site.
Simplifying Googlebot`s job
Search Engine Roundtable’s executive editor, Barry Schwartz, caught a question on LinkedIn where an SEO professional asked Mueller to confirm whether he still recommends his past advice for larger sites to host images on separate domains to simplify Googlebot’s crawling job.
Here’s the question on LinkedIn:
Splitting the load can make sense
Google’s search advocate was quick to reply and gave this advice about when splitting the load across sub-domains or domains makes sense and how it applies to all content types:
- “If Google has trouble crawling as much as it wants to crawl due to technical reasons, then splitting the load across sub-domains or domains makes sense.”
- “Sometimes this makes sense for any kind of static content regardless of Google’s crawling (many sites have static content CDNs).”
Multiple domains don`t help rankings
Mueller went on to explain that most sites don’t need to split their content load, and doing so won’t help rankings anyway:
- “For most sites, this isn’t needed. (It won’t push Google to crawl more, and more crawling doesn’t mean better ranking.)”
Begging the question. If reducing your site’s content load by splitting it across multiple domains doesn’t assist Googlebot’s crawl capacity or your site’s ranking, why split your images/content at all?
Google’s Search Central documentation (large site owner’s guide to managing your crawl budget) covers that question:
What Google says about crawling capacity limit and demand:
- “Googlebot wants to crawl your site without overwhelming your servers. To prevent this, Googlebot calculates a crawl capacity limit, which is the maximum number of simultaneous parallel connections that Googlebot can use to crawl a site, as well as the time delay between fetches. This is calculated to provide coverage of all your important content without overloading your servers.”
- “Google typically spends as much time as necessary crawling a site, given its size, update frequency, page quality, and relevance, compared to other sites.”
No ranking benefit from using other domains
Mueller answered a similar question about the advantage of hosting images on your domain in March 2019, saying there’s no SEO benefit where you host them and using your domain or another domain won’t affect how well they rank:
Muller’s post on X:
- It doesn’t matter how you host the images; there’s no SEO bonus for having them on the same host/domain. However, since changing image URLs is hard, I’d use your own hostname for the CDN.”
The SEO professional finished by asking Mueller to confirm if “using a subdomain doesn’t create a separate prioritization queue for each subdomain from Googlebot’s perspective.”
Mueller avoided the question by admitting he didn’t know what the SEO meant and it’s technical:
Here’s the conversation on LinkedIn:
