Noob: Is there a "root" for IIS virtual dir?

I’m attempting to install a rails app as well as typo to virtual
directories of the same web site in IIS 6.

Problem is that URL’s in the browser page are missing virtual directory
“root”:

For example, with typo installed in “/blog”.
Typo link in browser: http://hostname/articles/category/mycategory
Typo link should say: http://hostname/blog/articles/category/mycategory

Have I missed a configuration setting (within rails)?

Many web application configurations have a “root” to set a base URL, in
this case it would be “/blog”. Is that available in rails?

Thanks.