Root server list
Kevin Darcy
kcd at chrysler.com
Wed Aug 13 22:44:07 UTC 2008
Andrey G. Sergeev (AKA Andris) wrote:
> Hello Scott,
>
>
> Wed, 13 Aug 2008 14:07:08 -0700 Scott Baker wrote:
>
>
>> If I run dig without any options it outputs a list of root servers:
>>
>> ;; ANSWER SECTION:
>> . 482765 IN NS K.ROOT-SERVERS.NET.
>> . 482765 IN NS E.ROOT-SERVERS.NET.
>> . 482765 IN NS L.ROOT-SERVERS.NET.
>> . 482765 IN NS M.ROOT-SERVERS.NET.
>> . 482765 IN NS J.ROOT-SERVERS.NET.
>> . 482765 IN NS H.ROOT-SERVERS.NET.
>> . 482765 IN NS I.ROOT-SERVERS.NET.
>> . 482765 IN NS F.ROOT-SERVERS.NET.
>> . 482765 IN NS G.ROOT-SERVERS.NET.
>> . 482765 IN NS B.ROOT-SERVERS.NET.
>> . 482765 IN NS A.ROOT-SERVERS.NET.
>> . 482765 IN NS C.ROOT-SERVERS.NET.
>> . 482765 IN NS D.ROOT-SERVERS.NET.
>>
>> Where does that information come from?
>>
>
> This data come from the server's cache which is initialized at the
> server startup using the named.root file (the hints). This file acts as
> a source of the names and IP addresses of the name servers holding the
> copy of "." (the root zone).
>
>
It's necessary to understand the concept of "priming". The hints file is
used as a source of, well, hints, about where to get the *real*
root-zone information. When the nameserver starts up, it uses the hints
to talk to a real root nameserver, gets the real root-zone information,
and then never uses the hints again (except perhaps if all of the root
records expire simultaneously?).
While it's true that you only need 1 working entry in "hints" to prime
and start running, it's safer and more efficient to periodically keep
the file up to date, as root server addresses change.
- Kevin
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