off-site slave servers? advice?

[Barry Margolin]

In article <cc189m$251l$1 at sf1.isc.org>,
 loren jan wilson <loren at uchicago.edu> wrote:

> So, here's the reason for my worry:
> We want another off-site nameserver because we want people to be
> able to reach our main website (which will be mirrored elsewhere)
> if we're down for an extended period of time. However, since bind 9
> doesn't seem to want to resolve domains where one of the nameservers
> doesn't respond, will having one off-site nameserver that is responding
> even help us if the other 5 are down?
> 
> Can anybody explain in detail how this is supposed to work, and give
> their opinion about whether or not we should be looking into this?

I can imagine problems that would occur if one of the servers is 
responding *incorrectly*, since this might not trigger failover.  
Different nameserver implementations do indeed have different criteria 
for when to try another nameserver if they get a failure response from 
the first one.

But if one of the servers simply stops responding, failover should 
always occur.  That's the whole point of listing multiple nameservers: 
to provide redundancy when nameservers or networks fail.

I suppose if you have lots of slave servers, you're increasing the 
likelihood of misconfigurations that could result in incorrect 
responses.  More servers and administrators increases overall 
complexity, which makes mistakes more likely.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***