Using root server...

Cihan Subasi (Garanti Teknoloji) CihanS at garanti.com.tr
Wed Jan 3 06:59:43 UTC 2001


When I increase the debug level to 3, I always see a.root server in the
logs, thats how I came up with this thought....I wouldn't control that
either but seemed to me ns always goes to a.root...Now I did some check
about RTTs of the root servers...I realized that all the root servers
resolve to the same ip (web.host.net - 205.166.250.18) maybe that could the
reason why always a.root in my logs...

-----Original Message-----
From: Jim Reid [mailto:jim at rfc1035.com]
Sent: Tuesday, January 02, 2001 7:24 PM
To: Cihan Subasi (Garanti Teknoloji)
Cc: bind-users at isc.org
Subject: Re: Using root server... 


>>>>> "Cihan" == Cihan Subasi (Garanti Teknoloji) <CihanS at garanti.com.tr>
writes:

    Cihan> 	How can I set the dns to use a specific root
    Cihan> server....Mine always uses a.root-servers.com to get the
    Cihan> gtld servers but is it possible to force the dns to use b
    Cihan> root or c root? Thanks....

When your name server starts it will pick one of the root servers at
random. After that, it will query whatever root server appears to
answer quickest. [In fact your server keeps track of the round trip
times (RTTs) for all zones where there's more than one name server for
the zone.] So if your name server is "always using a.root-servers.com"
- how do you know that? - the chances are that this is the name server
that generally answers the fastest for you. Your name server will
periodically forget the round trip times to all of the root
servers. This allows it to automatically adjust for name servers that
have got faster or slower - actually nearer or further away in routing
terms - since the last time it measured the RTTs.

Why do you care which root server your name server queries and why
would you want to control that? Personally, I'd leave the name server
to do this by itself. It can keep track of RTTs to other zone's name
server far better than anything or anyone else.



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