root name server and traffic

[Alex Shi]

Hi,

Thanks for your time to read my question.

My question is very basic and I am learning DNS now. The question might
be stupid but I really like to find out how.

Let's start with an example. A name server NS1 received a query for
www.abc.com. NS1 does not know www.abc.com so it send a query to root
name server. The root name server will tell NS1 which name server takes
care of www.abc.com. Let's say that NS2 knows www.abc.com.

To my understanding, the root name server must maintain a record to
answer this query. And this record must tell the querier that "NS2
knows www.abc.com". Why not directly tell the querier the IP address of
www.abc.com? It seems to me that a distributed DNS dababase does not
reduce much traffic and storage, but doubles them. the reason for my
opinion can be as following:

query: querier--->NS1--->root
answer: root--->querier
query again: querier--->NS2
answer: NS2--->querier

storage:  1. NS2: a record for www.abc.com
          2. root: a record about the name server of www.abc.com

I really want to know why we need a distributed DNS system. Please tell
me how.

Again thanks for your time.

Alex



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