how is a named resolved?

[flybird]

Hi,all
I have a question about how named is resolved.
For example, there is a DNS server "A" which manage a domain and is a cache
server for root domain. So while it get a query for aaa.bbb.com, it will
query root DNS "B". And suppose DNS for com is "C", DNS for bbb.com is "D".
And than will DNS "B" query the "C" for aaa.bbb.com or it just reply to "A"
that DNS for com is "C" and then "A" query "C" for aaa.bbb.com ?
There are tow figure below to help me express my question:

 1    2    3
---> ---> --->
A    B    C    D
<--- <--- <---
 6     5    4
    Figure 1

OR
 1
--->
A    B
<---
 2

 3
--->
A    C
<---
 4

 5
--->
A    D
<---
 6
Figure 2

In my impression, the flow of DNS query is Figure 1. But After i saw the
discuss "Private Public DNS question" in this group, it seems the flaw is
Figure 2. Now i don't know which one is true.
Thanx for any help,

Pan Tao