This sample chapter introduces the Windows Server 2003 implementation of WINS and DNS. You may learn the way to install and configure both name resolution services in addition to how to maintain and monitor them. Having a thorough knowledge of the subjects presented here is necessary to both the examination and on-the-job success.
Terms you will need to understand:
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Windows Web Naming Service (WINS)
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WINS Stand in Agent
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LMHOSTS
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Tombstoning
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Determined Connections
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Push/pull partner
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Hostnames
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Website name system (DNS)
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Recursive and iterative questions
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First, secondary, and stub sections
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Dynamic update
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Delegation
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Caching-only server
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Root name server
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Resource records
Methods you will have to master:
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Understanding NetBIOS name resolution methods
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Installing and configuring WINS
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Configuring a WINS stand in agent
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Configuring replication between WINS servers
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Handling and monitoring a WINS server
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Installing and configuring the DNS Server service
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Configuring sectors
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Understanding a caching-only server
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Understanding DNS section types
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Managing zones and resource records
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Implementing a delegated zone for DNS
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Monitoring a DNS server
Each machine on a computer network is allotted a completely unique network address. PCs communicate with one another across networks by connecting to these network addresses. These numbers, sometimes called Internet Protocol (IP) addresses, are composed of four groups of numbers, or octets, and can be tough for folks to remember. To unravel this quandary, a system was developed whereby people can use “friendly” names that are then interpreted automatically into IP addresses that computers use to locate one another and to speak. These friendly names are called hostnames, and each machine is assigned one. Groups of these hosts form a domain. The software that interprets these names to network addresses is called the Domain Name System (DNS).
Before the advent of DNS, HOSTS files were used for name resolution, but as the Net quickly grew in size and popularity, HOSTS files became not possible to maintain and keep current. When the Net community realized there had been a requirement for a more manageable, scalable, and efficient name-resolution system, DNS was made. Since then, DNS servers have been utilized online almost exclusively.
Before the advent of Windows 2000, Network Basic Input/Output System (NetBIOS) names were utilized in identifying PCs, services, and other resources on Windows-based machines. In the early days of Windows networks, LMHOSTS files were used for NetBIOS name resolution. Later , these names were regularly resolved to IP addresses using a NetBIOS Name Server (NBNS). Microsoft’s version of the NBNS was called Windows Net Naming Service (WINS). With Windows 2000 and Windows Server 2003, hostnames are used rather than NetBIOS names. In a Windows Server 2003 domain, DNS is used to resolve hostnames and locate resources like network services.
This chapter introduces the Windows Server 2003 implementation of WINS and DNS. You'll learn how to install and configure both name resolution services along with how to maintain and monitor them. Having an inclusive understanding of the subjects presented here is necessary to both the examination and on-the-job success.
Introduction to NetBIOS Name Resolution
Some clients still depend on NetBIOS names to talk with other hosts on a network. A NetBIOS name is a 16-character name where the first 15 characters identify a singular. Host and the 16th character identifies a service or application running on the host such as the Workstation or Server service. Table 3.1 outlines common hexadecimal values utilized in identifying services running on a computer.
Table 3.1. Node Types
Node Type
Outline
Registered by the Workstation service
Suggests a website name that can be employed to find domain controllers
Registered by a PC running Routing and Remote Access
Registered by each domain controller functioning as the domain master browser
Registered by a WINS client running the Server service
Registered by the RAS customer running on a WINS customer
As with site names, NetBIOS names must be determined to an IP before 2 hosts can communicate. There are a number of different techniques available for name resolution and the method employed will depend upon the environment.
Name Resolution Strategies
The three standard techniques of resolving NetBIOS names to IP addresses are through a local broadcast, using the local cache, or by using a NetBIOS name server.
With a local broadcast, a broadcast is sent out on the network asking for the IP number of a particular host. The obvious disadvantage to this strategy is the rise in traffic.
All hosts maintain a local cache that can be used for name resolution. Each time a host resolves a NetBIOS name to an IP address, the record is added to the local cache and remains valid for 10 minutes. By default, all clients will check their local cache before using any of the other resolution techniques available.
The third choice is to utilize a NetBIOS name server (such as a WINS server) to resolve names to IP addresses.
In a Microsoft environment, a number of other methods for resolving names are also available such as DNS servers, HOSTS files, and LMHOSTS files.
Dependent on the requirements of an environment, clients can be designed to use a single technique for name resolution or they can use a mixture of strategies. The exact technique a client uses to decide NetBIOS names is determined by their node type. For instance, if a customer is configured as an M-Node, it'll try to resolve a NetBIOS name by first performing a local broadcast. If this is unsuccessful, it will then try and resolve the name using a NetBIOS name server. You can check the node type a customer is configured for by typing ipconfig/all at the command prompt. The node type can be modified within the local Registry. Table 3.2 summarizes the 4 different node types.
Table 3.2. Node Types
Node Type
Outline
B-Node
A broadcast is employed for NetBIOS name registration and resolution.
P-Node
A NetBIOS name server is employed for name registration and resolution.
M-Node
A broadcast is attempted first for name resolution. If this technique fails, a NetBIOS name server is contacted.
H-Node
A NetBIOS name server is tried first for name resolution. If this fails a broadcast is employed.
TIP
Remember that before performing a broadcast or establishing contact with a WINS server, the host will try to resolve a NetBIOS name utilizing its local cache.
Exam Alert
Be ready to encounter examination questions applying to the NetBIOS node types. Make sure you are conversant with what methods of resolution are used for each type and in what order.
Examination Alert
A Windows Server 2003 or Windows XP customer that is configured as a DHCP customer mechanically uses H-Node for NetBIOS name resolution. This implies the customer will try to resolve NetBIOS names employing a WINS server first before using a local broadcast (after checking the local cache). The customer will resolve names in the following order: local cache, WINS, broadcast, LMHOSTS, HOSTS, DNS.
LMHOSTS Files
As already discussed, one of the ways that NetBIOS names can be resolved is thru the usage of a text file known as an LMHOSTS file. One of the advantages of using an LMHOSTS file is that entries from the file can be pre loaded into the local cache to expedite name resolution (because this is the strategy a client will use to solve a NetBIOS name). So if a client can't resolve a NetBIOS name using any of the methods described formerly, it can parse the LMHOSTS file to see whether a record exists.
TIP
Remember that in order for clients to deal with names using an LMHOSTS file, they've got to be configured to do so (refer to the section “Configuring WINS Clients” for more information).
The LMHOSTS file can be found in the %systemroot%system32driversetc list. When configuring records within the file, there are several directives that can be used which are made public in Table 3.3.
Table 3.3. Predefined Directives That Can Be Used. Inside an LMHOSTS File
Predefined Keyword
Outline
Pre
Outlines which entries in the file should be loaded into the local cache.
DOM: domain_name
Indicates the record is for a domain controller.
Begin_Alternate
Specifies a listing of other locations for an LMHOSTS file.
End_Alternate
inlcude
Loads entries from another LMHOSTS file separate from the default file on the local computer. This option is most frequently used to designate a positioned centrally LMHOSTS file.
MH
Adds multiple entries for a multihomed PC.
Examination Alert
Be sure that you are acquainted with the various directives that can be utilised inside an LMHOSTS file and what their purposes are.
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