Secondary queried?

[Barry Margolin]

In article <a6855m$qr8 at pub3.rc.vix.com>, Smithz <mav102 at hotmail.com> wrote:
>
>With primary and secondary I mean authoritative for the zone.  Thank
>you for the explanation of stub and full resolver.  The remaining
>question I have is this scenario.  Lets say a "stub resolver" queries
>their ISP name server for a domain that it does not have local or
>cached knowledge for that domain and does not have a forwarder
>configured.  At this point the queried name server looks to the
>primary authoritative name server of the domain.  If the primary does
>not have the zone configured, will the name server making the query
>bother to check the secondary authoritative name server or will it
>give up and say "domain not found"

First of all, it doesn't necessarily go to the primary authoritative
server, since it doesn't know which is primary and which is secondary.  All
it has is a list of NS records for the domain, with no priority order
specified.

It will query one of those servers, and if it doesn't get a response it
will query another one, and so on until it runs out of servers.

If it gets a response containing an answer, or an authoritative response
indicating that the record doesn't exist, it will cache it and return the
answer to its client.

If it gets a "Server Failure" response, I think the exact behavior probably
depends on the specific version of software running on the ISP's name
server.  I think some versions will simply forward this error response back
to the client, while others will perform failover to one of the other
servers.  As a result, when you have inconsistencies among the servers that
a domain is delegated to, problems tend to be transient and inconsistent;
things will seem fine coming from one ISP, but screwy from another.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Woburn, MA
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