Name Server Types
If a name server hosts a certain type of zone, the name server is typically referred to as that type of name server. For instance, if you configure a name server to host a primary zone named ZoneA, the name server would be called a primary name server for ZoneA. The types of name servers you can configure on a computer running the Windows 2000 DNS service are the same as the zone types previously listed, as well as two other types:
Master (for a standard zone)Any name server that hosts a primary or secondary copy of a zone database and is also responsible for sending updated copies of the database to other name servers is known as a master name server.
Caching-onlyA caching-only name server does not host any zone databases and does not respond to queries from other name servers, but it does perform name resolution for client resolvers.
A DNS name server can be used to host several zones, so the name server can be a primary name server for one zone and a secondary name server for a different zone. If the name server hosts the primary name server for a zone, it is a master name server for that zone by default.
Primary Name Server
A name server that is a primary name server maintains a zone database file. Any changes made to the zone are made to the primary zone database file, and then replicated to any secondary name servers for that zone. In addition to maintaining the information for the zone, the primary name server also responds to queries from client computers on its network and other name servers on the Internet. Figure 3.1 shows a primary name server for 501.redtab.com.
Figure 3.1 Primary name server for the 501redtab.com domain.
To create a new primary zone on a Windows 2000 DNS server, from the DNS tool (located in the Administrative Tools menu), you start the New Zone Wizard, select Standard Primary, and complete the wizard. By default, the wizard will create a file with the same name as the zone, place the file in the systemroot\system32\dns directory, and create SOA (Start of Authority) and NS (Name Server) resource records in the zone file. After any changes are made to the zone database file, a backup copy of the file is created in systemroot\system32\dns\backup. Along with the file being created in the folder, a key is added to the Registry HKLM\SYSTEM\CurrentControlSet\Services\DNS\zones\zonename for each zone created.
SOA, NS, and several other types of records are discussed in detail in Chapter 8, "Exploring Resource Records."
After the Primary zone is created, you can configure and update the zone using the DNS tool located on the Administrative Tools menu. While using the DNS tool is the preferred method, you can also edit the zone files directly using a text editor.
Secondary Name Server
Before you can create a secondary zone database, the primary zone must already be created on another name server. To create a new secondary zone database file, start the New Zone Wizard in the DNS tool, select Standard Secondary, and complete the wizard. Once created, the zone will be populated with the records from the master name server from which you will receive the zone transfers.
Figure 3.2 shows Server1 hosting the standard primary zone for the 501redtab.com zone with a secondary server named Server2 being configured as a secondary name server.
Figure 3.2 A primary server for the 501redtab zone named Server1, which is also the master server for Server2. Server2 is the master server for Server3.
Server1 is primary and master for server 2.
Server2 is secondary with Server1 acting as master and updating Server2.
Server3 is secondary with server2 acting as master and updating server 3.
Server2 is configured with Server1 as its master; therefore, Server2 receives its zone updates from Server1. Server3 is configured as a secondary name server for the 501redtab.com zone and is configured to use Server2 as its master. Therefore, Server3 receives its zone updates from Server2.
Master Name Server
A master name server provides zone updates to a secondary name server. Both standard primary and standard secondary zones can be master name servers, and there is no additional configuring needed to make a name server a master name server. In Windows 2000, you must list all the name servers for a zone in the primary zone database using NS resource records. To do this using the DNS tool, do the following:
From the Administrative Tools menu, click DNS.
Right-click the primary zone you want to list the name servers for, and then click Properties.
Under the Name Servers tab, add the name servers that will host the zone database file.
The NS resource records will be created automatically when you add them to the name server list. After the name servers for the zone are listed on the name server tab, each time you create a secondary zone, you can provide the address of any of the name servers listed, thus making the server listed a master for the secondary you are creating.
A caching-only name server is used to provide name resolution client resolvers in a small, remote office with limited network bandwidth. A caching-only name server does not host any zone database files; therefore,
Network traffic responding to queries from other name servers will not be generated.
Network traffic using supporting zone file updates will not be generated because a caching-only name server does not host any zone files.
Network traffic generated by client resolver queries will be reduced. When a caching-only name server resolves a query for a client resolver, the results are stored in the name server's cache. The name server will use the information stored in cache to resolve other resolver queries.
To create a caching-only name server, install the DNS service but do not configure any zones. Configure client computer's TCP/IP properties to use the DNS server you configured for name resolution.
Active Directory Integrated
To create an Active Directory Integrated zone, you use the DNS interface and New Zone Wizard just as you would to create a standard primary or standard secondary zone. The option to create an Active Directory Integrated zone will be available if your DNS service is running on a domain controller. When you create an Active Directory Integrated zone, you view and manage the zone using the DNS tool.
The zone is stored as a dnsZone container in Active Directory, and any resource records in the zone are stored as dnsNodes in the container for their zone, as shown in Figure 3.3.
To view the zone and any resource records for the zone, do the following:
From the Administrative Tools menu, open Active Directory Users and Computers.
On the View menu, click Advanced Features.
In the Active Directory Users and Computers console tree, expand System, and then expand MicrosoftDNS. The Active Directory Integrated zone will be listed. Click the zone you want to view, and the resource records will appear in the details pane.
Figure 3.3 Active Directory Integrated zone being viewed using Active Directory Users and Computers.
Active Directory Integrated zones use a multiple master model, so any domain controller for a Windows networking domain that has the DNS service installed and the zone configured in DNS can manage a zone database. This provides fault-tolerance because there is no single point of failure for the zone as there is with a standard primary zone.
You can configure a standard secondary zone, even if the primary zone is an Active Directory Integrated zone. Because the DNS service provided with Windows 2000 is RFC-compliant, you can configure any RFC-compliant DNS name server as a secondary server for an Active Directory Integrated zone.
You can create an Active Directory Integrated reverse lookup zone that works in the same manner as an Active Directory forward lookup zone. As with the Active Directory Integrated forward lookup zone, the reverse lookup zone is stored in Active Directory, and standard secondary in-addr.arpa zones can be configured to use the Active Directory reverse lookup zone for the master (see Figure 3.4).
Figure 3.4 DNS Manager with an in-addr.arpa (reverse lookup zone) displayed.