Chapter 5:
Servers and Networks - Linux: This Book Includes 4 Manuscripts. The Underground Bible to the unix operating...

Chapter 5:
Servers and Networks
The US introduced the first computer network in 1996. It was a big deal
because it was the first of its kind and created new ways of connecting
computers. It also lay the foundation for the development of the Internet.
Previously, computer networks were limited and performed limited
functions. Today they have been developed to include a wide range of
devices. The purpose of servers is to ensure that information flows between
computer networks.
A server can be a system or computer that gives data to other computers
through networks. Other computers that servers share information are
called clients. There are different types of servers, including virtual servers,
mail servers, and web servers. One system has the capacity to give data and
use them across systems in the same period. This implies that a device can
act as a client and server concurrently. The first servers were different from
what is in the market today. They were minicomputers or mainframe
computers and were smaller in size. When technology was advanced, they
became larger than desktops.
They were no longer minicomputers but microcomputers. During the initial
stages, people connected servers to terminals, types of servers, that did not
do a good job. The role of the terminals was to receive input through a
keyboard and return the outcome to a printer. Its limited role affected the
overall function of devices. Computing was done on servers. Things
changed over time, and servers could be connected to single and powerful
computers over a network to less-powerful client computers.
The situation where both the server and the client computer have the
computing powers is known as the client-server model. However, some
tasks are assigned to the server in the client-server model. Previously, the
mainframe-terminal model acted as a server although it was not known by
that name. The meaning and use of a server have evolved as technology
progressed.
It can now perform more tasks than it did in the beginning. It has reached
an extent where servers can be software on computer devices. Servers who
are installed as software are known as virtual servers. Initially, virtual
servers were employed to improve the number of server functions. It has
progressed to become a multi-purpose software. Virtual servers can now be
run by a third party on hardware through the Internet. Cloud computing
comes in handy when dealing with virtual servers. Servers can be created to
perform single or multiple tasks. A mail server is an example of a single
task performed by a server. Print and file servers are examples of several
tasks performed by servers.
Devices are configured to listen to requests from clients to work as a
server. It must also be connected to a network and can be installed as an
application. If you use Microsoft’s Windows server, you get to listen and
respond to the client’s request. It is also suitable because it sends requests
to clients over the network. It receives and responds to requests with the
right information. Some applications are notorious for responding with the
wrong information, thereby affecting the entire process. This server is
known as the call and response model. Servers perform several tasks such
as checking the identity of the person who sent a request and ensuring that
the client is allowed to access information.
Different servers perform different functions. Networks have more than one
type of server. Types of servers include file servers, print servers,
application servers, mail servers, DNS servers, and web servers. A web
server is one of the most abundant types of servers. It is a type of server
that hosts data requests and programs across the Internet. They respond to
client requests from the browser operating on a client computer for
websites. Examples of web servers include Microsoft Information Services,
Apache Web Servers, and Nginx Servers. Mail servers are used as
application servers. They are common and used by many.
The work of a mail server is to receive emails sent to users and keep them
until they are requested by the client. Therefore, it is the duty of the mail
server to store emails and keep them in good condition until they are
demanded by the user. A mail server enables the configuration of a single
machine and attaches it to a network at all times. Once the configuration
process is done, it is ready to send and receive messages instead of
expecting every client machine to have email subsystems running all the
time. DNS (Domain Name System) Servers provide name resolutions to
client computers by changing names that humans understand easily into
machine-readable IP addresses. It comes in handy because it helps when the
client wants the address of the system.
Another type of server is proxy servers. It is an intermediary between a
server and a client. It is commonly used to isolate the client servers for
security reasons. The proxy server receives the feedback from the second
serve application and replies to the first client. Servers use client servers to
run applications. They are used to run intensive applications shared by
many users. It eliminates the need for every client to have enough
resources to run applications. It also removes the burden to find and run
applications. Users are also free from the burden of installing and
maintaining software on many computers. Print servers facilitate the
management and distribution of printing functions. Instead of attaching
printers in all workstations, one print is enough to do all the work. It has
the ability to respond to printing requests from several clients.
Moreover, some high-end printers come with built-in servers that cater for
the cost of printing services. It removes the burden of buying computer-
based print servers. Another type of server is the file server, which stores
and distributes files. Many clients can share files kept on a server.
Furthermore, storing files offer backup in case users lose sensitive
information. The server hardware can be built in such a way that they
maximize read and write speeds to promote efficiency. Virtual servers are
not here to play. They are taking over the world, and users have started
noticing. Virtual servers are defined in specialized software known as a
hypervisor. Hypervisors run on thousands of virtual servers at once. Virtual
servers are considered the best servers the world has ever seen. The
hypervisor gives virtual hardware to the server in a similar manner to
physical hardware. It uses the virtual hardware and passes the computation
to the actual hardware underneath that is shared by other virtual servers.
Computer networks are put into three categories based on the size, the
structure, and distance. The categories include LAN, WAN, and MAN.
Two devices are considered to be in-network if the process in one can share
information with another. They are also referred to as mediums of
connections between nodes or machines. Networks comprise of computer
systems, networking devices, and servers that are linked together to
exchange information. Wireless media can be used to connect computer
systems. Types of computer networks are discussed below.
❖
LAN (Local Area Network)
LAN is a privately own computer network that covers a small geographical
area of networks such as offices, homes, schools. It is used to connect
computing devices to enable the exchange of information. Devices
connected in LAN can share a wide range of information and build strong
connections. LAN is small in size compared to other types of networks and
devices are connected to central devices known as Hub via a cable. Today,
wireless technologies can be used to install LANs and uses access points to
send and receive data. In some cases, one computer acts as a server and
caters to all the computers called Clients.
For instance, libraries can have wired LAN networks for users to connect
local networking gadgets. They can connect servers and printers to connect
to the Intranet or Internet. There are two types of LANs, namely Ethernet
and ARCnet. ARCnet is the simplest, oldest, and most affordable type of
LAN. It was commonly available for microcomputers and gained popularity
in the 1980s. The good this with ARCnet is that it allows different kinds of
transmission media to be part of the same network. Ethernet is the second
type of LAN, and it is a family of computers that networking techs for
LAN. It was introduced in 1980 and grew to replace wired local network
techs. It uses a star or bus topology network. It also supports the transfer of
data at the rates of 10 Mbps. It uses the SCMA/CD access technique to
tackle demands that come at the same time. It is the most implemented
LAN standard in history. 100Base-T is the new version of the Ethernet
network.
❖
MAN (Metropolitan Area Networks)
MAN is bigger than LAN and occupies the area of one city. It rare for them
to go beyond 100 KM and consists of a mixture of transmission and
hardware media. MAN can an individual network like a cable TV network.
It is based on the IEE 802 standard method called DQDB. It employs two
unidirectional cables and connects all the machines to them.
Standardization and security are the two most important aspects of the
Metropolitan Area Network. Security plays a vital role because data is
being shared between dissimilar systems. In such cases, it is important to
put everything in order and prioritize security. Standardization is crucial
because it ensures reliable data communication. Users must ensure that the
two aspects are taken care of. MAN interconnects many LAN using via
high capacity links and avail link services to the Internet. Protocols are
found at the data link level that is explained by ITU-T, or IEEE.
❖
WAN (Wide Area Network)
WAN serves as a telecommunication network is a network of networks. It
connects LANs that are on opposite sides of structures and across the
world. They are known to have the slowest data communication rate.
Moreover, they have the largest distance. There are two types of WANs,
namely, Global WAN and an enterprise WAN. WANs are typically
connected to public networks, satellites or leased lines. The Internet is the
largest WAN in existence. Certain parts of the Internet, such as VPN are
considered to be WANs. Several WANs have been created including
banking networks, corporate networks, and stock brokerage networks.
Firms that support WANs through the Internet Protocol are called Network
Service Providers and forms the basis of the Internet. WANs use costly
networking equipment compared to MAN or LAN. They use Frame
Relays, ATM, and SONET. An enterprise WAN is preferred because it
connects the whole firm, including LAN sites. The term is used by large
organizations, governments or universities.
On the other hand, Global WANs also reach the whole world, but it is not a
must for them to connect to LANs in a firm. An example of a Global WAN
is the Internet because it connects different areas, institutions, and
organizations across the world. Global WANs can either be public or
private, where the latter is called Intranet that belongs to a firm. The former
is open to everyone, and people have access to resources.
❖
WLANs- Wireless Local Area Network
WLANs are also known as LAWN, which stands for Local Area Wireless
Network. It gives wireless network communication over a short distance.
It uses infrared or radio signals to provide wireless networks instead of
traditional network cables. WLANs provide a framework for users to
connect to local area networks via wireless connections. It extends to a
wired local area network and is developed by attaching a device known as
the access point to a wired network. Users communicate with the access
point through a wireless network adapter that works similar to a traditional
Ethernet adapter. One of the most important issues for WLANs is network
security .
To ensure security, Random wireless clients are denied access to WLAN.
Components that have the ability to connect into a wireless medium are
referred to as stations. The stations have wireless network interface
controllers. There are two types of WLAN, Private home and Enterprise-
class WLAN. Enterprise-class WLAN uses several access points to
broadcast signals to wide areas. These access points have many features
apart from small offices or homes. A private home WLAN employs one or
two access points to broadcast a signal. Most retail stores have tools for
installing home or small office WLAN. Another type of network is SAN
(Storage Area Network). It is a kind of LAN with high speed and special
use networks. It facilitates data storage and replication on business
networks via servers. SANs technology resembles network-attached
storage.
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