How to handle a blog subdomain on the main sitemap and robots file?

[seo.owl]

Hi,

I have some confusion about how our blog subdomain is handled in our sitemap.  We have our main website, example.com, and our blog, blog.example.com.

1. Should we list the blog subdomain URL in our main sitemap?  In other words, is listing a subdomain allowed in the root sitemap?

2. What does the final structure look like in terms of the sitemap and robots file?  Specifically:

**example.com/sitemap.xml **

would I include a link to our blog subdomain (blog.example.com)?

example.com/robots.xml

would I include a link to BOTH our main sitemap and blog sitemap?

blog.example.com/sitemap.xml

would I include a link to our main website URL (even though it's not a subdomain)?

blog.example.com/robots.xml

does a subdomain need its own robots file?

I'm a technical SEO and understand the mechanics of much of on-page SEO.... but for some reason I never found an answer to this specific question and I am wondering how the pros do it.  I appreciate your help with this.

[Ryan-Bradley]

It's my understanding that you treat each subdomain as a unique site. So each subdomain should have its own unique XML sitemap and robots.txt file, as well as submitted separately to Google Webmaster Tools. But to answer your inter-linking question, I would avoid including the other domain URLs in those files (XML and Robots). Only include the URLs for that particular domain and/or subdomain. With that being said however, I would inter-link them on the actual site somewhere. Maybe in the HTML sitemap, navigation, footer, or even naturally throughout your body content where appropriate as well.