Re: [cobalt-developers] Re: Secondary DNS

["Kevin D" <kdlists@xxxxxxxxxxxxxxx>]

I think there's a slight problem with this "hack"... if DNS is functioning
on the primary but the www service is not, the failover won't work because
that primary DNS server will still be serving the (possibly) dead www
server. I suppose its good if an entire server/connection goes down, though.

I'm looking into clustering with piranha or microsoft clustering services.
Does anyone have any experience with clustering raq3's (NOT staqware) ?

Kevin

----- Original Message -----
From: "Norbert Bollow" <nb@xxxxxxxxxxxxxx>
To: <cobalt-developers@xxxxxxxxxxxxxxx>
Sent: Saturday, December 02, 2000 2:20 AM
Subject: Re: [cobalt-developers] Re: Secondary DNS


> > I would appreciate your thoughts on that - if my RAQ and its primary DNS
> > are up, but Internic has a secondary DNS in place of my primary #, and
that
> > secondary is down, do browsers (or whatever the mechanism is) *know* to
> > look at the other DNS server or do they just report a server not found
error?
>
> The DNS system is designed so that the "closest" nameserver (in
> some sense) is tried first, but as long as at least one of
> your primary and secondary nameservers is working and reachable,
> all name lookups will work.
>
> So suppose you have two servers, let's call them 'primary' and
> 'secondary', with IP addresses XXX.XXX.XXX.XXX and YYY.YYY.YYY.YYY.
> Set them up so that 'secondary' exactly mirrors all the websites
> at 'primary'. Run named on both servers, but *not*
> in the usual configuration of master and slave, but configure
> both as masters, with different zone files, as follows:
>
>
> On the 'primary' server:
>
> ; DNS hack for two webservers so that if one server is down or
> ; unreachable, the other is guaranteed to have completely taken
> ; its place within five minutes. -- nb@xxxxxxxxxxxxxx
> @                IN   SOA     primary.example.com. hostmaster.example.com.
(
>                               2000120201            ; Serial
>                               10800                 ; Refresh
>                               1800                  ; Retry
>                               3600000               ; Expire
>                               300    )              ; Minimum TTL
>           604800 IN   NS      primary.example.com.
>   604800 IN   NS      secondary.example.com.
>           604800 IN   MX   10 primary.example.com.
>           604800 IN   MX   20 secondary.example.com.
>      300 IN   A       XXX.XXX.XXX.XXX
> primary   604800 IN   A       XXX.XXX.XXX.XXX
> secondary 604800 IN   A       YYY.YYY.YYY.YYY
> www       604800 IN   CNAME   example.com.
>
>
> On the 'secondary' server:
>
> ; DNS hack for two webservers so that if one server is down or
> ; unreachable, the other is guaranteed to have completely taken
> ; its place within five minutes. -- nb@xxxxxxxxxxxxxx
> @                IN   SOA     secondary.example.com.
hostmaster.example.com. (
>                               2000120201            ; Serial
>                               10800                 ; Refresh
>                               1800                  ; Retry
>                               3600000               ; Expire
>                               300    )              ; Minimum TTL
>           604800 IN   NS      primary.example.com.
>   604800 IN   NS      secondary.example.com.
>           604800 IN   MX   10 primary.example.com.
>           604800 IN   MX   20 secondary.example.com.
>      300 IN   A       YYY.YYY.YYY.YYY
> primary   604800 IN   A       XXX.XXX.XXX.XXX
> secondary 604800 IN   A       YYY.YYY.YYY.YYY
> www       604800 IN   CNAME   example.com.
>
>
>
> It is then important that you list primary.example.com. and
> secondary.example.com. and nothing else as nameservers.
>
> I'm available to help you with setting this up properly
> (including mirroring and mail relaying) if desired, for an
> hourly fee.
>
> Warm greetings, Norbert.
>
>
> --
> Comparitive list of colo providers http://thoughtcenter.com/colocation
> Norbert Bollow, Weidlistr.18, CH-8624 Gruet (near Zurich, Switzerland)
> Tel +41 1 972 20 59       Fax +41 1 972 20 69        nb@xxxxxxxxxxxxxx
>
>
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