Path redundancy

[Jeff Lightner]

Is there a way to setup preferred and secondary entries for RRs other
than MX?
Situation:

We have two IP ranges (legs) provided to us by AT&T.   The first leg
defines a wider/faster pipe so in normal use would be the one on which
all traffic would flow.   The other leg would be used only in the event
the primary leg goes down for whatever reason.

We want to have DNS servers in the second leg so that in the event of
failure of the first leg resolutions would still occur.   However the
IPs for our internet facing systems would now be those of the second
leg.   (I'm being told the only way we could NAT is if we let AT&T have
a router on their side that does it so we'd have a single point of
failure.)    

Currently it seems we'd have to have a master DNS server in each leg
with the zone file of the first one knowing about the first leg IPs for
the internet facing systems and the second server knowing about the IPs
for the second leg IPs for the internet facing systems.   This seem like
a bad idea because there would be no way to insure people weren't using
the second leg when the first is up and second it means external sites
that checked to be sure everything was in agreement on all our DNS
servers would of course complain that it isn't.

Note:  The REAL IPs assigned to the NICs wouldn't change - we'd route
the internet address IPs from either leg to the REAL IPs internally.

Jeffrey C. Lightner
Unix Systems Administrator
DS Waters of North America
678-486-3516