Hierarchical file names always start at the top of the tree. Consider, for example, the file name

Question:

Hierarchical file names always start at the top of the tree. Consider, for example, the file name /usr/ast/books/mos2/chap-12 rather than chap-12/mos2/books/ast/usr. In contrast, DNS names start at the bottom of the tree and work up. Is there some fundamental reason for this difference?