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 https://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 https://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.
