newbie: which server answers

[Barry Margolin]

In article <bn93vs$1cf3$1 at sf1.isc.org>, Yaro <adminsun_no-spam_ at wp.pl> wrote:
>Hi,
>
>I am trying to understand the idea of dns and I have
>one simple (?) question:
>
>let's say there is a domain named: domain.info and
>there are four servers defined as authoritative
>name servers for this domain. This information
>is saved in root servers for top domain "info".
>Each of these servers is correctly configured and ready
>to give answers to dns-queries regarding domain.info.
>
>the question is:
>Which server will be queried by clients the most often?

The one that answers fastest.  BIND records the response times of previous
queries to a server, and when it has to select among a set of servers for a
domain it chooses the one with the best record.  However, it does a "fuzzy"
comparison; if several servers have response times that are close to each
other, it treats them as equal, and chooses arbitrarily among them (I don't
know offhand if it's random or round-robin -- either way you can expect
approximately equal volume).

Note that the one that answers fastest may be different for different
clients.  If you have servers located far apart on the Internet (as the
servers for the root domain and most of the generic TLDs are), it's likely
that the fastest response will come from the server closest to a particular
client.

-- 
Barry Margolin, barry.margolin at level3.com
Level(3), Woburn, MA
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