Types of DNS Servers

DNS is an integral and necessary part of any Windows Active Directory implementation. In addition, it has evolved to be the primary naming service for the Unix OS and the Internet. Because of Microsoft's decision to make Windows Server 2000 (and Windows Server 2003) Internet-compatible, DNS has replaced WINS as the default name resolution technology. Microsoft followed IETF standards and made its DNS server compatible with other DNS implementations .

Unix BIND DNS

Many organizations have significant investment in Unix DNS implementations. Microsoft Exchange heavily relies on Active Directory, and Active Directory heavily relies on DNS. Microsoft Active Directory can coexist and use third-party DNS implementations as long as they support active updates and SRV records. In some cases, organizations choose not to migrate away from the already implemented Unix DNS environment; instead, they coexist with Microsoft DNS. Companies using coexisting Unix and Microsoft DNS environments should consider the following:

• The Unix DNS installation should be at least 8.1.2.

• For incremental zone transfers, the Unix DNS implementation should be at least 8.2.1.

Third-Party (Checkpoint-Meta IP or Lucent Vital QIP) DNS

Third-party DNS implementations can provide significant enhancements in enterprise class IP management. They either provide integrated management of Unix, Linux, and Microsoft DNS and DHCP servers from a central location or can be used in place of the previously mentioned implementations. Latest versions fully support dynamic DNS updates, SRV records, and Incremental Zone Transfer, which should be considered a necessity if Active Directory uses the third-party DNS servers.

DNS Compatibility Between DNS platforms

DNS clients should, in theory, be able to query any DNS server regardless of who wrote that implementation. Active Directory, in particular, has some unique requirements from all DNS servers, however. Clients that authenticate to Active Directory look specifically for server resources, which means that the DNS server has to support SRV records. In Active Directory, DNS clients can dynamically update the DNS server with their IP address using Dynamic DNS. It is important to note that Dynamic DNS is not supported by all DNS implementations.

NOTE

In a mixed DNS environment, Microsoft specifically recommends using Microsoft DNS server as the primary DNS server and all others as secondary. Microsoft reasons that its implementation is the newest and more likely to be backward-compatible with older DNS implementations.