CHAPTER 9
IMPLEMENTATION WINDOWS INTERNET
NAME
SERVICE (WINS)
Although Microsoft Windows Internet Name Service (WINS) servers are not needed to a
networking consisting entirely of Microsoft Windows 2000-based computers, they are crucial
in most Transmission Control Protocol/Internet Protocol (TCP/IP) networks containing
computers based on the older architectures of Windows NT 4.0, Windows 98, or Windows 95.
Lesson 1:
Introduction to WINS
WINS provides a distributed database for registering and querying dynamic mappings of
NetBIOS names for computers and groups used on your network. WINS maps NetBIOS
names to IP addresses and was designed to solve the problems arising from NetBIOS name
resolution in routed environments. WINS is the best choice for NetBIOS name resolution in
routed networks that use NetBIOS over TCP/IP.
Name Resolution with NetBIOS
NetBIOS was developed for IBM in 1982 by Sytek Corporation to allow applications to
communicate over a network. NetBIOS defines two entities:
The NetBIOS interface is a presentation-layer application programming interface (API) for user
applications to submit network input/output (I/O) and control directives to underlying network
protocols.
Net BIOS provides commands and support for the following
services:
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NetBIOS Names
A NetBIOS name is a unique 16-byte address used to identify a NetBIOS resource on the
network. This name is either a unique (exclusive) or group (nonexclusive) name.
Group names are used to send information to multiple computers at one time. An example,
of a process that uses a NetBIOS name is the File and Printer Sharing for Microsoft Networks
service on a computer running Windows 2000. The exact name used by the service is the
15-character computer name plus a 16th character of 0X20. If the computer name is not
15 characters long, it is padded with spaces up to 15 characters.
NetBIOS name resolution is the process of mapping a computer’s NetBIOS name to an IP
address. A computer’s NetBIOS name must be resolved to an IP address before the IP address
can be resolved to a hardware address.
Microsoft TCP/IP uses several methods to resolve NetBIOS names; however, the exact
mechanism by which NetBIOS names are resolved to IP addresses depends on the NetBIOS
node type that is configured for the node.
Computers running Windows 2000 are B-node by default and become H-node when they are
configured with a WINS server. Windows 2000 can also use a local database file called
LMHOSTS to resolve remote NetBIOS names. The LMHOSTS file is stored in the
%systemroot%\System32\Drivers\Etc folder.
IN CLASSROOM NOTES:
the remote host. Ignore the local ones, so specify remote in the LMHOSTS file.
already on the system.
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deregister the database. If you do not log on properly , it keeps the same IP address.
tombstone if it is stagnant too!
TCP/IP.
That is why in My Network Places/Local Area Connection/Properties/ TCP/IP/Properties/Advanced
/WINS tab you will see (enable NetBIOS over TCP/IP) and (disable NetBIOS over TCP/IP).
If you are using WINS you must “enable NetBIOS over TCP/IP
The LMHOSTS File
The LMHOSTS file is a static ASCII file used to resolve NetBIOS names to IP addresses of remote
computers running Windows NT and other NetBIOS-based hosts.
*** See the
predefined keywords on page 203 ***
WINS Overview
WINS eliminates the need for broadcasts to resolve computer names to IP addresses and provides
a dynamic database that maintains mappings of computer names to IP addresses. WINS is an
enhanced NetBIOS name server (NBNS) designed by Microsoft to eliminate broadcast traffic
associated with the B-node implementation of NetBT.
The primary advantage of WINS is that client requests for computer name resolution are sent
directly to a WINS server. If the WINS server can resolve the name, it sends the IP address
directly to the client.
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WINS and Windows 2000
Prior to Windows 2000, all MS-DOS and Windows-based operating systems required the
NetBIOS naming interface to support network capabilities. With the release of Windows 2000,
support for the NetBIOS naming interface is no longer required for networking computers because
you can disable NetBT for each network connection.
Another example is an environment consisting of host computers and programs that support the
use of DNS that could be built to run using Windows 2000 and other operating systems not
requiring NetBIOS names, such as some versions of UNIX. However, most networks still
need to integrate legacy operating systems that require NetBIOS network names with computers
running Windows 2000. For this reason, Microsoft has continued to provide default support for
NetBIOS names with Windows 2000 to ease interoperability with legacy operating systems that
require their use. This support is provided mainly in two ways:
By default, all computers running Windows 2000 that use TCP/IP are enabled to provide client-
side support for registering and resolving NetBIOS names.
This support is provided through NetBT and can, if desired, be manually disabled.
Windows 2000 Server continues to provide server-side support through WINS. WINS can
be used to effectively manage NetBT-based networks.
Lesson Summary:
resources.
with the B-node implementation of NetBT.
Lesson 2:
The WINS Resolution Process
Wins uses standard methods of name registration, name renewal, and name release.
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Resolving NetBIOS Names with WINS
When a client needs to contact another host on the network, it first contacts the WINS server
to resolve the IP address using mapping information from the database of the server. The
relational database engine of the WINS server accesses an indexed sequential access method
(ISAM) database.
The process WINS uses to resolve and maintain NetBIOS names is similar to the B-node
implementation. The method used to renew a name is unique to NetBIOS node types that
use a NetBIOS name server. WINS is an extension of RFCs 1001 and 1002.
Name Registration
Each WINS client is configured with the IP address of a primary WINS server and optionally,
a secondary WINS server. When a client starts, it registers its NetBIOS name and IP address
with the configured WINS server.
Name Renewal
All BetBIOIS names are registered on a temporary basis, which means that the same name can
be used later by a different host if the original owner stops using it.
Name Release
Each WINS client is responsible for maintaining the lease on its registered name. When the
name will no longer be used, such as when the computer is shut down, the WINS client sends
a message to the WINS server to release it.
Name Query and Name Resolution
After a WINS client has registered its NetBIOS name and IP address with a WINS server,
it can communicate with other hosts by obtaining the IP address of other NetBIOS-based
computers from a WINS server. All WINS communications are done using datagrams over
UDP port 137 (NBNS).
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Name Registration
Unlike the B-node implementation of NetBT, which broadcasts its name registration, WINS
clients register their NetBIOS names with WINS servers.
If the WINS server is available and the name is not already registered by another WINS client,
a successful registration message is returned to the client. This message contains the amount of
time the NetBIOS name is registered to the client as a TTL or time to live.
When a Duplicate Name is Found
If there is a duplicate name registered in the WINS database, the WINS server sends a challenge
to the currently registered owner of the name.
If the registered computer is a multihomed computer, the WINS server tries each IP address it
has for the computer until it receives a response or until all or the IP addresses has been tried.
When the WINS Server is unavailable
A WINS client will make three attempts to find the primary WINS server. If it fails after the
third attempt, the name registration request is sent to the secondary WINS server, if configured.
Name Renewal
To continue using the same NetBIOS name, a client must renew its lease before it expires. If a
client does not renew the lease, the WINS server makes it available for another WINS client.
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Name Refresh Request
WINS clients must renew their name registrations before the renewal interval expires. When a
WINS client refreshes its name, it performs the following steps:
to the primary WINS server.
refresh again in 10 minutes and continues repeatedly every 10 minutes for a total of 1 hour.
name again using the secondary WINS server in 10 minutes, then tries in 10 minute
intervals for up to an hour.
server.
5. If the WINS client fails to register during the renewal interval on either the primary or
secondary WINS server, the name is released.
Name Release
When a WINS client is properly shut down, it sends a name release request directly to the
WINS server for each registered name.
When the WINS server receives the name release request, it checks it database for the
specified name. If the WINS server encounters a database error or if a different IP address
maps the registered name, it sends a negative name release to the WINS client. The name
release response contains the released NetBIOS name and a TTL value of zero.
Name Query and Name Response
A common method of resolving NetBIOS names to IP addresses is with an NBNS, such as
WINS. When a WINS client is configured, by default, the H-node type of NetBT is used.
checked for the NetBIOS name/IP address mapping of the destination host.
If the name is not resolved from cache, a name query request is sent directly to the client’s
primary WINS server.
client with the message “Requested name does not exits,” and broadcast is implemented.
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Lesson Summary:
To continue using the same NetBIOS name, a client must renew its lease before it expires.
NetBIOS name.
Lesson 3:
Implementing WINS
For networks with servers running Windows 2000 Server and all other computers running
Windows 2000 Professional, NetBIOS is no longer required for TCP/IP-based networking.
When to Use WINS
When deciding whether you need to use WINS, you should first consider the following questions:
Do I have any legacy
computers or applications on my network that require the use of NetBIOS
names?
Remember that all networked computers that run under any previously released Microsoft
operating system, such as versions of MS-DOS, Windows, or Windows NT, require NetBIOS
name support. Windows 2000 is the first Microsoft operating system that no longer requires
NetBIOS naming. Therefore, NetBIOS names can still be required on your network to provide
basic file and print services and support for many legacy applications used.
Are all computers on
my network configured and able to support the use of another type of
network naming, such
as DNS?
Network naming is still a vital service for locating computers and resources throughout your
network, even when NetBIOS names are not required. Before you decide to eliminate
WINS or NetBIOS name support, be sure that all computers and programs on your
network are able to function using another naming service, such as DNS.
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Is my network a
single subnet or routed with multiple subnets?
If your entire network is a small local area network (LAN) that occupies one physical network
segment and has less than 50 clients, you can probably do without a WINS server.
Considerations for WINS Servers
Before you implement WINS in an internetwork, consider the number of WINS server you
will need. Two WINS servers ensure a backup system for fault tolerance. You should
also consider the following:
There is not built-in limit to the number of WINS requests that can be handled by a WINS
server, but typically it can handle 1500 name registrations and about 4500 name queries/minute.
One WINS server and a backup server for every 10,000 WINS clients.
Computers with multiple processors have demonstrated performance improvements of
approximately 25% for each additional processor, as a separate WINS thread is started
for each processor.
If logging of database changes is turned off, name resolution is much faster.
WINS Requirements
Before you install WINS, you should determine that your server and clients meet the
configuration requirements. The WINS service must be configured on at least one computer
within the TCP/IP internetwork running Windows NT Server or Windows 2000 Server
(it does not have to be a domain controller).
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A WINS client can be a computer running any of the following
supported operating systems:
The client must have an IP address of a WINS server configured for a primary WINS server
or for primary and secondary WINS servers.
Using Static mappings
Mapped name-to-address entries can be added to WINS in either of two ways:
Dynamically, by WINS-enabled clients directly contacting a WINS server to register, release,
or renew their NetBIOS names in the server database.
Manually, by an administrator using the WINS console or command-line tools to add or delete
statically mapped entries in the server database.
Troubleshooting WINS
The following conditions can indicate basic problems with
WINS:
(stop and restart the services).
a network connectivity problem between the client and the WINS server.
The most common WINS server problem is the inability to resolve names for clients. When a
server fails to resolve a name for its clients, the failure most often is discovered by clients in one
of two ways:
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indicating “Name not found”.
response is incorrect.
Managing and Monitoring WINS
The WINS console is fully integrated with the Microsoft Management Console (MMC), a
powerful and more user-friendly environment you can customize for your efficiency.
Lesson Summary:
To implement WINS, both the server and client require configuration.
Configuring a static mapping for non-WINS clients allows WINS clients on remote networks
to communicate with them.
When troubleshooting WINS, the first action you should take is to verify that the appropriate
services are running.
Lesson 4:
Configuring WINS Replication
All WINS servers on an internetwork can be configured to fully replicate database entries
with other WINS servers. This ensures that a name registered with one WINS server is
eventually replicated to all other WINS servers.
Replication Overview
Database replication occurs whenever the database changes, including when a name is
released. Replicating databases enables a WINS server to resolve NetBIOS names of
hosts registered with another WINS server.
To replicate database entries, each WINS server must be configured as either a pull or
push partner with at lease one other WINS server. A push partner is a WINS server that
sends a message to its pull partners notifying them when its WINS database has changed.
When a WINS server’s pull partners respond to the message with a replication request, the
WINS server sends a copy of its new database entries (replicas) to its pull partners.
NOTE: WINS servers replicate only new entries in their database. The entire WINS
database is not replicated each time replication occurs.
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Configuring a WINS Server as a Push or Pull Partner
Determining whether to configure a WINS server as a pull or push depends on your
network environment.
Push. When servers are connected by fast links, because push replication occurs when the
configured number of updated WINS database entries is reached.
Pull. Between sites, especially across slow links, because pull replication can be configured
to occur at specific intervals.
Push/Pull. Configure each server to be both a push and pull partner to replicate database
entries between them.
NOTE: You configure a WINS server as a push or pull partner with the WINS
administration tool.
In both Sydney and Seattle, all WINS servers at each site push their new database entries
to a single server at their site.
The servers that receive the push replication are configured for pull replication between
each other because the network link between Sydney and Seattle is relatively slow.
Replication should occur when the link is the lease used, such as late at night.
WINS Automatic Replication Partners
If your network supports multicasting, the WINS server can be configured to automatically
find other WINS servers on the network by multicasting to the IP address 224.0.1.24.
This multicasting occurs by default every 40 minutes. The routers must support this, and
hey must be set up in the registry.
Backing up the WINS Database
The WINS console provides backup tools so that you can back up and restore the WINS
database. When WINS backs up the server database, it creates a \Wins_bak\New folder
under the backup folder you have specified as the Default backup path in Server Properties.
Actual backups of the WINS database (WINS.MDB) are stored in this folder. By default,
the backup path is the root folder on your system partition, such as C:\. After you specify a
backup folder for the database, WINS performs complete database backup every three
hours using the specified folder.
IMPORTANT: Do not specify a network drive as the backup location. In addition, if you
change the WINS backup or database path in server properties, perform new backups to
ensure successful future restorations of the WINS database. This is the only way for the
active WINS database to be backed up, because the database is locked open while the
WINS server is running.
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Lesson Summary:
All of the WINS servers on a given network can be configured to communicate with each
other so that a name registered with one WINS server will eventually be known by all
WINS servers.
CLASSROOM NOTES: *** IMPORTANT ***
Why do we use a DHCP on the other side of the router.
DHCP uses a relay agent to go past the router client subnet A will not go past router.
*** BROADCASTS DO NOT GO PAST ROUTERS ****
WINS
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetBT\Paramenters
“enable proxy = 1 (hexadecimal)
DO NOT CHANGE JUST VIEW SETTINGS.
IP filter is used to ensure that only people who are supposed to dial in are using this service.
Protocol is based on applications used.
Dial-in can be controlled.
PPTP and L2TP prevents being hacked into.
P294. RAS goes to DHCP grabs bank of 10 addresses.
IAS is 2000 version of RADIUS.
RADIUS is used for user authentications
4As, Authentication, accounting, auditing and authorization.