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MCSA/MCSE Self-Paced Training Kit (Exam 70-270): Installing ...

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Lesson 2 Understanding the Domain Name System<br />

13-31<br />

Multiple name servers act as a backup to the name server containing the primary zone<br />

database file. Multiple name servers provide the following advantages:<br />

Lesson Review<br />

■ They perform zone transfers. The additional name servers obtain a copy of the<br />

zone database file from the name server that contains the primary database zone<br />

file. This process is called a zone transfer. These name servers periodically query<br />

the name server containing the primary zone database file for updated zone data.<br />

■ They provide redundancy. If the name server containing the primary zone database<br />

file fails, the additional name servers can provide service.<br />

■ They improve access speed for remote locations. If there are a number of clients<br />

in remote locations, use additional name servers to reduce query traffic across<br />

slow wide area network (WAN) links.<br />

■ They reduce the load on the name server containing the primary zone database<br />

file.<br />

Real World Active Directory and DNS<br />

Active Directory and DNS are tightly integrated—they even share a common<br />

namespace. It is essential, therefore, that you understand how each system works<br />

and how they work together.<br />

DNS is the locator service used by Active Directory (and by many other Windows<br />

components). Active Directory makes its services available to the network by<br />

publishing them in DNS. When a domain controller is installed (or when services<br />

are added to it), the domain controller uses dynamic updates to register its services<br />

as SRV records in DNS. Clients can then locate services through simple DNS<br />

queries. The Microsoft DNS Service runs on every Windows Server 2003 domain<br />

controller by default.<br />

The following questions are intended to reinforce key information presented in this<br />

lesson. If you are unable to answer a question, review the lesson materials and try the<br />

question again. You can find answers to the questions in the “Questions and Answers”<br />

section at the end of this chapter.<br />

1. What is DNS and what is it used for?

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