Re: DNS problem (forwarding order?)

[Dan Williams <dcbw redhat com>]

On Thu, 2005-07-07 at 14:47 -0700, David MacMahon wrote:
> Dan Williams wrote:
> > But NetworkManager doesn't control which nameservers get used first, it
> > just dumps them to bind/caching-nameserver.  So NetworkManager isn't
> > really doing wrong stuff here, its the behavior of bind that's causing
> > the problem...
> 
> If NetworkManager is taking an order-is-significant list from DHCP and 
> using it as an order-is-not-significant list in named.conf, then 
> NetworkManager is doing wrong stuff.  The question I've not yet 
> resolved, so to speak :-), is whether or not order is significant in the 
> named.conf file's forwarders option.  If order is supposed to be 
> significant in named.conf, then bind seems to have a problem.  If order 
> is not significant in named.conf, then NetworkManager seems to have a 
> problem.
> 
> > It just so happens that we have a much more intelligent
> > resolver now than with glibc.
> 
> Can you please expand on that?  I suppose local caching is a slight 
> benefit, but is there anything else that makes using named preferable to 
> just putting...
> 
> nameserver ns1
> nameserver ns2
> nameserver ns3
> 
> ...into /etc/resolv.conf?

1) (as already mentioned) changes are not immediately visible to running
applications, it sucks to have to either quit and relaunch mozilla, or
to wait 1 minute for stuff to work
2) apps in the middle of a DNS query return immediately and don't wait
the full 30s timeout for DNS queries
3) Split DNS allows us to only resolve certain domains with certain
servers, as opposed to everything through 1 server.  Useful for VPN
where we want only *.redhat.com to go to Red Hat DNS, everything else
through our local nameserver from DHCP

Dan