Examining the Current Name Resolution Infrastructure

Every network needs to have some method of resolving computer names to network addresses. Two name resolution methods exist within a Windows Server 2003 network infrastructure: the Domain Name System (DNS) and Windows Internet Name Service (WINS). We will look at each of these in the following sections.

The Domain Name System (DNS) is a name resolution method that is used extensively within Windows 2000 Server and Windows Server 2003 networks as well as the Internet and other network operating systems. Clients and servers can send queries to a DNS server in order to resolve a hostname to an IP address so that two systems can communicate with each other. If you are going to implement Active Directory, you must have DNS within a Windows Server 2003 network. The Active Directory domain structure is based on the DNS domain structure. Domain controllers require DNS servers so that they can register service locator (SRV) records. Clients and applications will send queries for the SRV records when they are trying to locate a domain controller. Of course, many other applications need to have a DNS server so that they will function correctly, such as web services and e-mail systems.

Companies that have Internet access will have DNS servers that they use in order to access resources on the Internet. These DNS servers could be owned and maintained by the organization, but the servers could be maintained just as easily by an outside company like their Internet Service Provider (ISP). You will need to determine how the company is currently using DNS as a name resolution solution.

If you currently host services that users from the Internet will access, or you are planning on allowing access to your resources at a later time, you need to make sure that the users will be able to locate your Internet name. You must register your Internet presence with an Internet registration authority so that you are ensured of owning your domain name. If you do not register your domain name, another company could register it and use it.

You essentially have two choices when determining how you will employ your DNS infrastructure: you could host your own DNS servers and maintain the DNS zones yourself, or you could have your ISP maintain your zones on their servers. For some companies, having an ISP host their DNS infrastructure may seem like the perfect fit. The ISP typically has administrators who are experienced with DNS and how to maintain it, and the organization does not have to support its own servers or train its administrative staff on another technology.

If you do decide to outsource your DNS implementation, you must make sure that the ISP has the appropriate DNS infrastructure to support your needs. You must also determine whether the ISP s infrastructure is secure enough to host critical information about your internal network. Chances are, you will not want an ISP to host your internal domain information. It is not advisable to have another organization hosting information on their servers that is critical to your network s availability. You should host your own DNS servers and make sure they are located close to the domain controllers and users that need them. Some of your domain controllers may also run the DNS service on them. As we discuss server placement options later in this chapter, we will look at how you should design your systems.

You could have a mixed environment that has internal DNS servers to support the organization s internal name resolution requirements and an ISP that hosts a DNS that the organization uses for external name resolution to Internet resources. Utilizing this method, the organization can outsource some of the DNS maintenance. Administrators from the organization can concentrate on maintaining their own infrastructure and allow the outside entity to maintain the services they are experienced in running.

Windows Internet Name Service (WINS) has been used extensively by Microsoft operating systems as a way to resolve computer names to IP addresses. Until the Windows 2000 product line, all of the Microsoft operating systems relied on NetBIOS name resolution from WINS servers. Therein lies the difficulty in trying to remove NetBIOS from a network so that it can rely solely on DNS for name resolution; too many applications and operating systems still need to use NetBIOS.

Because NetBIOS is so prevalent within today s networks, you will usually find a WINS infrastructure in place to assist with NetBIOS name resolution for clients and servers that reside in different subnets. Before you make any changes to the network infrastructure, you should determine where you have located WINS servers and which systems use these servers for name resolution.

The current DNS and WINS infrastructure will help you determine how the name resolution services are currently used by the organization. You should create a diagram of your name resolution environment that includes the DNS and WINS servers. This diagram should also specify which clients use each of the servers in your infrastructure. Chances are, the clients will continue to use the same servers.

Also take note of the types of DNS servers that are currently in use. Many companies have already implemented a DNS infrastructure using a third-party DNS solution. If this is the case, you may find yourself having to fight another battle ”trying to get Microsoft DNS integrated into the environment. For years UNIX DNS solutions have controlled the DNS infrastructure in many organizations. If this is the case in your organization, you may find yourself having to use the existing infrastructure. In the next section, we will look at the options you have if a third-party DNS solution is already in place.

When diagramming the WINS solution, take note of the current replication topology. When you understand how the servers replicate to one another, you can better understand the importance of each site. For instance, you may have several remote locations that use WINS to register and query computer names. Two of the sites regularly share information. The replication schedule for these two sites is set so that replication occurs between them in short intervals. The other sites do not share as much data, so the replication interval is set so that the link is not used as often. Replication options are discussed in this chapter under the Designing a Name Resolution Server Infrastructure section.

In the next section, we will identify the options that make up a DNS namespace. Organizations that need to provide Internet users access to part of their organization s resources will need to determine how they are going to design their internal and external domain names. Once the domain name requirements have been determined, you will need to decide how the DNS infrastructure will support your requirements.