Workgroup:
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In computer networking, a workgroup
is a collection of computers on a local area network (LAN) that share
common resources and responsibilities. Workgroups provide easy sharing of
files, printers and other network resources.
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Being a peer-to-peer (P2P)
network design, each workgroup computer may both share and access resources if
configured to do so.The Microsoft Windows family of operating systems supports
assigning of computers to named workgroups.
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Macintosh networks offer a similar
capability through the use of AppleTalk zones. The Open Source software
package Samba allows Unix and Linux systems to join existing Windows
workgroups.
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Workgroups are designed for small LANs
in homes, schools, and small businesses. A Windows Workgroup, for
example, functions best with 15 or fewer computers.
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As the number of computers in a
workgroup grows, workgroup LANs eventually become too difficult to administer
and should be replaced with alternative solutions like domains or other
client/server approaches.
Binary Based:
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The binary based model is one that is used by Novell NetWare
versions up to NetWare 3.2 binary based networks follow the client/server model
of networking.
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Novell binary based servers still have a large presence in
many networks to this day. In a binary
model, there is one server and many clients.
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The server contains a flat user account database. A flat user account database is one that
contains the names of users, in one single list from A to Z who are allowed to
log onto the system.
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Also, this database of user accounts is used to assign who
has rights or privileges to use different resources on the network. These rights are either assigned on a
user-by-user basic or a group-by-group basic.
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The server is also responsible for containing all of the
services on the network. The client
machines are not designed to provide any services at all. This allows for a more centralized method of
management of the network.
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A client machine on this system is one that has a redirector
installed on it, such that it will connect to a central server, and try to
authenticate against that server’s user account database.
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The user will supply a valid name that exists within the user
account database(logon name) and an associated password.
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If the name and password exist within the server’s user
account database, the user is granted permission to use the network, and in
turn, the user’s computer is given a “key” by the authenticating server.
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This key is similar to a security badge that you may wear
when touring a secured facility.
Limitation
of binary model:
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Binary models do not allow for the sharing of database lists
between servers, as each server maintains its own user account database.
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Because of this limitation, as more servers are added to the
network, every time a new user account is created, it would have to be added to
the user account database on each server that would contain a resource being
shared out to that user.
Domain:
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The DNS translates Internet domain and
host names to IP addresses. DNS automatically converts the names we type in our
Web browser address bar to the IP addresses of Web servers hosting those sites.
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DNS implements a distributed database to
store this name and address information for all public hosts on the Internet.
DNS assumes IP addresses do not change (are statically assigned rather than
dynamically assigned).
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The DNS database resides on a hierarchy
of special database servers. When clients like Web browsers issue requests
involving Internet host names, a piece of software called the DNS resolver
(usually built into the network operating system) first contacts a DNS server
to determine the server's IP address.
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If the DNS server does not contain the
needed mapping, it will in turn forward the request to a different DNS server
at the next higher level in the hierarchy.
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After potentially several forwarding and
delegation messages are sent within the DNS hierarchy, the IP address for the
given host eventually arrives at the resolver, that in turn completes the
request over Internet Protocol.
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DNS additionally includes support for
caching requests and for redundancy. Most network operating systems support
configuration of primary, secondary, and tertiary DNS servers, each of which
can service initial requests from clients.
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Internet Service Providers (ISPs)
maintain their own DNS servers and use DHCP to automatically configure clients,
relieving most home users of the burden of DNS configuration.
Directory
Services:
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A simple directory service called a naming service, maps the
names of network resources to their respective network addresses. With the name
service type of directory, a user doesn't have to remember the physical address
of a network resource; providing a name will locate the resource.
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Each resource on the network is considered an object on the
directory server. Information about a particular resource is stored as
attributes of that object.
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The directory design process normally has a set of rules that
determine how network resources are named and identified. The rules specify
that the names be unique and unambiguous.
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In X.500 (the directory service standards) and LDAP the name
is called the Distinguished name (DN) and is used to refer to a
collection of attributes (relative distinguished names) which make up the name
of a directory entry.
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A directory service is a shared information infrastructure
for locating, managing, administering, and organizing common items and network
resources, which can include volumes, folders, files, printers, users, groups,
devices, telephone numbers and other objects.
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A directory service is an important component of a NOS
(Network Operating System).
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In the more complex cases a directory service is the central
information repository for a Service Delivery Platform. For example, looking up
"computers" using a directory service might yield a list of available
computers and information for accessing them.
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