Page 71 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Exposure to Computer Disciplines

Notes 4.3.1.2 Client/Server Networks
Server based networks, or client/server networks as they are properly called, has a machine at
the heart of its operations called the server. A server is a machine that provides services over a
network by responding to client requests. Servers rarely have individuals operating it, and even
then, it is usually to install, configure or manage its capabilities. The server’s essential role on
the network is to be continuously available to handle the many requests generated by its clients.
Server-based networks provide centralised control of the entire network environment. The
computer systems used for this role are generally more powerful than end-user machines,
incorporating faster CPUs, more memory, larger disk drives and other drive types installed, like
a tape drive for backup purposes. These are required, because servers are dedicated to handling
multiple simultaneous requests from their client communities.
Server based networks provide centralised verification of user accounts and passwords. Only
valid account name and password combinations are allowed access to the network. Client/
Server networks typically require a single login to the network itself, meaning that users need to
remember long password lists to access various resources. Concentrations of resources on a single
server, mean that they are easier to find, as opposed to the peer-to-peer model, were resources
were distributed throughout the network since they were attached to multiple machines. The
server being a central data repository, means that not only is data more accessible to users, but it
also makes life much easier in terms of performing backups, since the data is in a location know
to the administrator.
Server-based networks are easier to scale. Peer-to-peer networks bog down seriously as they grow
beyond ten users, and serious slow up with 20 users. On the other hand, client/server networks
can handle a few users, up to a thousand users as such networks grow to keep pace with an
organisations growth and expansion.
Unlike peer-to-peer networks, client/server networks don’t come cheap. The server machine itself
may cost several thousands of pounds, along with the software to make it run; another thousand
pounds. Because of the complex nature of this kind of networking environment, a dedicated
administrator is required to be on site at all times to be involved in the day to day running of
the network. Hiring an individual of this nature adds considerably to the cost of client/server
networks.
Lastly, because the networks operability is so dependent upon the server, this introduces a single
point of failure, if the server goes down the network goes down. There are measures available, that
can legislate for such failures, and however these techniques add even more cost to this solution.

Figure 4.3: Client-Server Network

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