primary&secondary

Kevin Darcy kcd at daimlerchrysler.com
Sat Jul 15 03:39:19 UTC 2000


Mark Drummond wrote:

> Kevin Darcy wrote:
> >
> > "Primary" and "secondary" were used by BIND (previous to BIND 8) to denote
> > "master" and "slave", so your nomenclature understandably caused confusion.
> > Just something to keep in mind for future communication...
>
> Will do, it is a habit. OTOH, I've read much documentation that refers
> to the 1,2,3 entreis in resolv.conf as you primary, secondary and
> tertiary servers. Confusion reigns supreme ...

That wouldn't happen to be Microsoft documentation, would it? I think they are a
major source of the confusion in this area.

> > Sixty seconds? That's bogus. Resolver failover on Solaris is more on the
> > order of 5 seconds.That doesn't help when I have over 2000 Windows PCs to
> deal with.

Huh? You said earlier that your boss thought that "Windows handle[s] this
better". So is it the Windows boxes that have the ~60sec failover or something
non-Windows? OBTW, my Win95 box here at work has about a 5-second resolver
failover delay also. Maybe mine is at a different Service Pack level :-[ Or
maybe your fallback DNS server is overloaded/misconfigured/just-plain-slow.

> > This is why I run caching-only nameservers everywhere I can, even on
> > "client"-type machines. It makes name resolution *far* more robust.
>
> Perhaps I could add a caching server config to my jumpstart'ed lab Sun
> workstations, that handles maybe 50-60 of the UNIX boxes. And I really
> don't care about the HPs since we no longer support them. Hmm, good
> idea! Would DJB's dnscache serve here as well? We are just converting
> from Autoclient to Jumpstart so perfect opportunity for something like
> this.
>
> > By the way, the newer resolver libraries allow you to specify "rotate" in
> > the resolver configuration, which causes queries to be spread amongst the
> > configured nameservers -- no more "primary" and "secondary", eh? -- and
> > this should in theory make name resolution more robust. But I still think
> > caching-only nameservers is a superior solution.
>
> By this you mean there is something I can put into the resolv.conf on my
> UNIX boxen to enable this?

I don't know that any vendors have yet adopted the resolver libraries which
implement "rotate" (although admittedly I haven't looked at Solaris 8 yet, and
I don't look at AIX at all if I can help it). And as Jim Reid pointed out,
because system resolvers are typically implemented as libraries on Unix,
"rotate" doesn't really help many/most client programs that do a single lookup
during their lifetime. (This should change when BIND 9's "lwresd" is
implemented). "rotate" should help non-Unix platforms and some Unix daemons
though...


- Kevin




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