hi, this is my main site. (for an example) http://www.mysite.com/ i added a sub domain like : http://pictures.mysite.com/ and added link to http://pictures.mysite.com/ in the homepage , navbar on main site : http://www.mysite.com/ will google crawl it automatically ? or should i required to submit site maps ? Please Advice. Thank You.
If these subdomains will have backlinks from indexed pages, they will be indexed in some time too.(~2 weeks or so).
a subdomain isn't much different then mysite.com/subpage, its all about the links to it. Google doesn't look at it like a top level domain although i think yahoo might give subdomains more credit then subpages for some reason.
it will index, all web pages crawl by spiders but of course it takes some time, site map is used for spider to easy navigate your site its like a map for spider were to crawl with regards to your site.
Exactly, if you provide nevigation sub domains from home page then your sub domain will be indexed soon. But if your home page is not cached then you have to submit your sub domains into sitemap.xml and also verify it into google webmaster tool
Site map helps in crawling.it you palced link on indexed page, search engine will crawl thses page too.