BN206 System Administration: Comprehensive Analysis of Networking

This report provides a comprehensive overview of computer networking, starting with the basic definitions of computer networks, nodes, and data transfer rates. It explores the client/server model, different types of networks including LAN, WAN, and MAN, and various network topologies such as ring, star, and bus. The report delves into internet connections, discussing internet backbones, ISPs, and technologies like phone modems, DSL, and cable modems. It also covers packet switching, open systems, the OSI Reference Model, and network protocols like TCP/IP, UDP, SMTP, FTP, and HTTP. Furthermore, the report addresses network security with firewalls and explores network addresses, the Domain Name System (DNS), and top-level domains. This resource is valuable for understanding the fundamental concepts of computer networking and system administration, particularly within the context of the BN206 course. Desklib provides access to similar solved assignments and past papers for students.

Networking
Computer network A collection of
computing devices that are connected in
various ways in order to communicate and
share resources
Usually, the connections between computers
in a network are made using physical wires or
cables
However, some connections are wireless,
using radio waves or infrared signals
15-1

Networking
The generic term node or host refers to any
device on a network
Data transfer rate The speed with which
data is moved from one place on a network to
another
Data transfer rate is a key issue in computer
networks
15-2

NetworkingComputer networks have opened up an entire
frontier in the world of computing called the
client/server model
15-3
Figure 15.1 Client/Server interaction

Networking
File server A computer that stores and
manages files for multiple users on a network
Web server A computer dedicated to
responding to requests (from the browser
client) for web pages
15-4

Types of Networks
Local-area network (LAN) A network that
connects a relatively small number of
machines in a relatively close geographical
area
15-5

Types of Networks
Various configurations, called topologies,
have been used to administer LANs
Ring topology A configuration that connects all
nodes in a closed loop on which messages travel in
one direction
Star topology A configuration that centers
around one node to which all others are connected
and through which all messages are sent
Bus topology All nodes are connected to a
single communication line that carries messages
in both directions
15-6

Types of Networks
A bus technology called Ethernet has become
the industry standard for local-area networks
Figure 15.2 Various network topologies
15-10

Types of Networks
Wide-area network (WAN) A network that
connects two or more local-area networks
over a potentially large geographic distance
Often one particular node on a LAN is set up to
serve as a gateway to handle all communication
going between that LAN and other networks
Communication between networks is called
internetworking
The Internet, as we know it today, is essentially
the ultimate wide-area network, spanning the
entire globe
15-8

Types of Networks
Metropolitan-area network (MAN) The
communication infrastructures that have
been developed in and around large cities
15-9

So, who owns the Internet?
Well, nobody does. No single person or
company owns the Internet or even controls it
entirely. As a wide-area network, it is made
up of many smaller networks. These smaller
networks are often owned and managed by a
person or organization. The Internet, then, is
really defined by how connections can be
made between these networks.
15-10

15-11
Figure 15.1 Local-area networks connected across a distance to
create a wide-area network

Internet Connections
Internet backbone A set of high-speed
networks that carry Internet traffic
These networks are provided by companies
such as AT&T, GTE, and IBM
Internet service provider (ISP) A
company that provides other companies or
individuals with access to the Internet
15-12

Internet Connections
There are various technologies available that you can
use to connect a home computer to the Internet
A phone modem converts computer data into an analog
audio signal for transfer over a telephone line, and then a
modem at the destination converts it back again into data
A digital subscriber line (DSL) uses regular copper
phone lines to transfer digital data to and from the phone
company’s central office
A cable modem uses the same line that your cable TV
signals come in on to transfer the data back and forth
15-13

Internet Connections
Broadband A connection in which
transfer speeds are faster than 128 bits
per second
DSL connections and cable modems are
broadband connections
The speed for downloads (getting data from
the Internet to your home computer) may not
be the same as uploads (sending data from
your home computer to the Internet)
15-14

Packet SwitchingTo improve the efficiency of transferring
information over a shared communication line,
messages are divided into fixed-sized, numbered
packets
Network devices called routers are used to direct
packets between networks Figure 15.4
Messages
sent by
packet
switching
15-18

Open Systems
Proprietary system A system that uses
technologies kept private by a particular
commercial vendor
One system couldn’t communicate with another,
leading to the need for
Interoperability The ability of software and
hardware on multiple machines and from
multiple commercial vendors to communicate
Leading to
Open systems Systems based on a common
model of network architecture and a suite of
protocols used in its implementation
15-16

Open Systems The International
Organization for
Standardization
(ISO) established the
Open Systems
Interconnection
(OSI) Reference
Model
Each layer deals
with a particular
aspect of network
communication
15-17
Figure 15.5 The layers of the OSI Reference Model

Network ProtocolsNetwork protocols are layered such that each
one relies on the protocols that underlie it
Sometimes referred to as a protocol stack
15-18
Figure 15.6 Layering of key network protocols

TCP/IP
TCP stands for Transmission Control
Protocol
TCP software breaks messages into packets,
hands them off to the IP software for delivery,
and then orders and reassembles the packets
at their destination
IP stands for Internet Protocol
IP software deals with the routing of packets
through the maze of interconnected networks
to their final destination
15-19

TCP/IP (cont.)
UDP stands for User Datagram Protocol
It is an alternative to TCP
The main difference is that TCP is highly
reliable, at the cost of decreased performance,
while UDP is less reliable, but generally faster
15-20

High-Level Protocols
Other protocols build on the foundation
established by the TCP/IP protocol suite
Simple Mail Transfer Protocol (SMTP)
File Transfer Protocol (FTP)
Telnet
Hyper Text Transfer Protocol (http)
15-21

MIME Types
Related to the idea of network protocols and
standardization is the concept of a file’s
MIME type
MIME stands for Multipurpose Internet
Mail Extension
Based on a document’s MIME type, an
application program can decide how to deal
with the data it is given
15-22

15-23
Figure 15.7
Some
protocols and
the ports they
use

Firewalls
Firewall A machine and its software that
serve as a special gateway to a network,
protecting it from inappropriate access
Filters the network traffic that comes in,
checking the validity of the messages as much
as possible and perhaps denying some
messages altogether
Enforces an organization’s access control
policy
15-24

15-25Figure 15.8 A firewall protecting a LAN

Network Addresses
Hostname A unique identification that
specifies a particular computer on the
Internet
For example
matisse.csc.villanova.edu
condor.develocorp.com
15-26

Network Addresses
Network software translates a hostname into
its corresponding IP address
For example
205.39.145.18
15-27

Network Addresses
An IP address can be split into
network address, which specifies a specific
network
host number, which specifies a particular
machine in that network
15-28
Figure 15.9
An IP address is
stored in four
bytes

Domain Name System
A hostname consists of the computer
name followed by the domain name
csc.villanova.edu is the domain name
A domain name is separated into two or more
sections that specify the organization, and
possibly a subset of an organization, of which
the computer is a part
Two organizations can have a computer named
the same thing because the domain name
makes it clear which one is being referred to
15-29

Domain Name SystemThe very last section of the domain is
called its top-level domain (TLD) name
15-30Figure 15.10 Top-level domains, including some relatively new ones

Domain Name System
Organizations based in countries other
than the United States use a top-level
domain that corresponds to their two-
letter country codes
15-31
Figure 15.11
Some of the top-level domain
names based on country codes

Domain Name System
The domain name system (DNS) is chiefly
used to translate hostnames into numeric IP
addresses
DNS is an example of a distributed database
If that server can resolve the hostname, it does
so
If not, that server asks another domain name
server
15-32