Your network contains two Active Directory domains named contoso.com and adatum.com.
The network contains a server named Server1 that runs Windows Server 2012 R2. Server1 has the
DNS Server server role installed. Server1 has a copy of the contoso.com DNS zone.
You need to configure Server1 to resolve names in the adatum.com domain. The solution must meet
the following requirements:
Prevent the need to change the configuration of the current name servers that host zones for
adatum.com. Minimize administrative effort.
Which type of zone should you create?

A.
Secondary

B.
Stub

C.
Reverse lookup

D.
Primary

Explanation:
When a zone that this DNS server hosts is a stub zone, this DNS server is a source only for
information about the authoritative name servers for this zone. The zone at this server must be
obtained from another DNS server that hosts the zone. This DNS server must have network access to
the remote DNS server to copy the authoritative name server information about the zone.

A stub zone is a copy of a zone that contains only necessary resource records (Start of Authority
(SOA), Name Server (NS), and Address/Host (A) record) in the master zone and acts as a pointer to
the authoritative name server. The stub zone allows the server to forward queries to the name
server that is authoritative for the master zone without going up to the root name servers and
working its way down to the server. While a stub zone can improve performance, it does not provide
redundancy or load sharing.

You can use stub zones to:
Keep delegated zone information current. By updating a stub zone for one of its child zones
regularly, the DNS server that hosts both the parent zone and the stub zone will maintain a current
list of authoritative DNS servers for the child zone.
Improve name resolution. Stub zones enable a DNS server to perform recursion using the stub
zone’s list of name servers, without having to query the Internet or an internal root server for the
DNS namespace.
Simplify DNS administration. By using stub zones throughout your DNS infrastructure, you can
distribute a list of the authoritative DNS servers for a zone without using secondary zones. However,
stub zones do not serve the same purpose as secondary zones, and they are not an alternative for
enhancing redundancy and load sharing.
There are two lists of DNS servers involved in the loading and maintenance of a stub zone:
The list of master servers from which the DNS server loads and updates a stub zone. A master
server may be a primary or secondary DNS server for the zone. In both cases, it will have a complete
list of the DNS servers for the zone.
The list of the authoritative DNS servers for a zone. This list is contained in the stub zone using
name server (NS) resource records.
When a DNS server loads a stub zone, such as widgets. tailspintoys.com, it queries the master
servers, which can be in different locations, for the necessary resource records of the authoritative
servers for the zone widgets. tailspintoys.com. The list of master servers may contain a single server
or multiple servers, and it can be changed anytime.
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