MCSA Windows Server 2012 R2 Complete Study Guide. Panek William

      To install DNS as a primary zone, you must first install DNS using the Server Manager MMC. Once DNS is installed and running, you create a new zone and specify it as a primary zone.

      Primary zones have advantages and disadvantages. Knowing the characteristics of a primary zone will help you decide when you need the zone and when it fits into your organization.

      Local Database

      Primary DNS zones get stored locally in a file (with the suffix .dns) on the server. This allows you to store a primary zone on a domain controller or a member server. In addition, by loading DNS onto a member server, you can help a small organization conserve resources. Such an organization may not have the resources to load DNS on an Active Directory domain controller.

      Unfortunately, the local database has many disadvantages:

      Lack of Fault Tolerance Think of a primary zone as a contact list on your smartphone. All of the contacts in the list are the records in your database. The problem is that, if you lose your phone or the phone breaks, you lose your contact list. Until your phone gets fixed or you swap out your phone card, the contacts are unavailable.

      It works the same way with a primary zone. If the server goes down or you lose the hard drive, DNS records on that machine are unreachable. An administrator can install a secondary zone (explained later in the next section), and that provides temporary fault tolerance. Unfortunately, if the primary zone is down for an extended period of time, the secondary server’s information will no longer be valid.

      Additional Network Traffic Let’s imagine that you are looking for a contact number for John Smith. John Smith is not listed in your smartphone directory, but he is listed in your partner’s smartphone. You have to contact your partner to get the listing. You cannot directly access your partner’s phone’s contacts.

      When a resolver sends a request to DNS to get the TCP/IP address for Jsmith (in this case Jsmith is a computer name) and the DNS server does not have an answer, it does not have the ability to check the other server’s database directly to get an answer. Thus it forwards the request to another DNS. When DNS servers are replicating zone databases with other DNS servers, this causes additional network traffic.