: How do services that make subsites (ie. new subdomains) get those sites indexed by Google and other search enginex? Services like tumblr, github pages, quora blogs, etc. make new subdomains when

Posted in: #Google #Googlebot #Indexing #Seo #Sitemap

Services like tumblr, github pages, quora blogs, etc. make new subdomains when a user signs up or makes a site.

So the subdomains are like: blogname.tumblr.com , pagename.github.io, blogname.quora.com, etc.

How do google and other search engines find out about these new sites?
Is it as simple as having a sitemap.xml file being "resubmitted" to google?

See support.google.com/webmasters/answer/183669?hl=en. I know that you can resubmit sitemaps to google via an HTTP request, but what about for new sites without a previously submitted sitemap?

Or do the owners of the subdomain (the user who set up the new site) have to submit their site manually via www.google.com/webmasters/tools/submit-url ?

Just getting started learning about SEO and how google crawls the web. Couldn't find anything that answer this (or I'm just bad at Google), hoping someone can answer. Thanks!

Edit:
I read through this: Why isn't my website in Google search results?
But the question still holds for sites where subdomains are generated dynamically.