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necessary (three record types) to identify the authoritative DNS servers for a zone (see
Figure 2.7). You should not use stub zones to replace secondary zones, nor should you use
them for redundancy and load balancing.
figure 2.7
DNS stub zone type
Stub zone databases contain only three record types: name server (NS),
start of authority (SOA), and glue host (A) records. Understanding these
records will help you on the Microsoft certification exams. Microsoft asks
many questions about stub zones on all DNS-related exams.
when to use Stub Zones
Stub zones become particularly useful in a couple of different scenarios. Consider
what happens when two large companies merge:
example.com
and
example.net
. In
most cases, the DNS zone information from both companies must be available to every
employee. You could set up a new zone on each side that acts as a secondary for the
other side's primary zone, but administrators tend to be very protective of their DNS
databases, and they probably wouldn't agree to this plan.
A better solution is to add to each side a stub zone that points to the primary server
on the other side. When a client in
example.com
(which you help administer) makes a
request for a name in
example.net
, the stub zone on the
example.com
DNS server would
send the client to the primary DNS server for
example.net
without actually resolving the
name. At this point, it would be up to
example.net
's primary server to resolve the name.
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