Assignment purposes. All messages travel through a ring

Assignment # 3


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ICT   CS-162







Q1. Write a
comprehensive note on the types of Network Topologies? Which one is the best in
your opinion and why?


Types of network topologies are given below with little



Bus topology
use a common backbone to connect all devices. It is a network type in e=which
computer and network device is connected to a single cable. It transmit data
only in one direction. Its advantage is that it is used in small networks and
easy to understand. One disadvantage is that if cables fails then whole network
fails and also cables have limited length.



In a ring
network, every device has exactly two neighbors for communication purposes.
All messages travel through a
ring in the same direction. Disadvantage is failure in any cable or device
breaks the loop and can take down the entire network. Advantage is transmitting network is not affected
by high traffic or by adding more nodes, as only the nodes having tokens can
transmit data.



In star topology
all the computers are connected to a single hub through a cable. This hub is
the central node and all others nodes are connected to the central node.
Advantage is every node has its
own dedicated connection to the hub and hub acts as a repeater for data flow.
Hub can be upgraded easily but it is expensive to use and cost of installation
is high.



It has a
root node and all other nodes are connected to it forming a hierarchy. It is
also called hierarchical topology. It should at least have three levels to the
hierarchy. In its simplest form, only hub devices connect directly to the tree
bus, and each hub functions as the root of a tree of devices. It is used in
wide area network. If
more nodes are added then maintenance is difficult. If central hub fails then
whole network fails.



topology introduces the concept of routes. Unlike each of the previous
topologies, messages sent on a mesh network can take any of several possible
paths from source to destination. A mesh network in which every device connects to every other
is called a full mesh. There
are two techniques to transmit data over the Mesh topology, one is routing and
other is  flooding. Advantage is each
connection can carry its own data load. It provides security and privacy.
Its disadvantage is that its installation
and configuration is difficult and cabling cost is more, also bulk wiring is



All these topologies have some advantages as well as
disadvantages. Best is that which suits you, which gives you friendly
environment to operate systems. All are best according to your need. Mesh
topology seems to be best because if any system stops working, it will not fail
the whole system but as I have already mentioned that it is costly and
difficult to handle.


Differentiate between Guided and Un-Guided Media? Discuss main types of
un-guided media? Give examples.


Guided Media

Guided media requires a physical path for

It is called wired communication or bounded
transmission media.

It provides direction to signal for travelling.

Its three types are:

Ø  Twisted
pair cable, coaxial cable and fiber optic cable.


Unguided Media

Unguided media is broadcasted through air or sometimes
through water.

It is called wireless communication or unbounded
transmission media.

It does not provide any direction for travelling.

Its main types are:

Ø  Radio wave,
microwave and infrared.


Types of Unguided Media

The unguided media is categorized into following types.

Radio Waves

The radio waves are generated easily, they are low-frequency
signals and can travel a long distance. The radio waves can penetrate through the

Micro Waves

The microwaves are transmitted in a straight line and hence
require the line-of-sight transmission. The distance covered by the microwave
signal depend on the height of the two antenna. More the taller are antennas
longer is the distance covered by the signal. The microwave has a frequency
higher than the radio waves. Microwave are used for telephone communication
mobile phones, television distribution, etc.




Infrared waves are used for short
range communication. Like, the remote control for televisions, VCRs, etc. uses
infrared waves. It cannot penetrate through obstacles. The government license
is not required, to operate an infrared system as it is more secure against


Q3. Discuss
generally the main security concerns to your computer while working in the
cyber world? Also, state some protective measures to safeguard your computer?


Malware is an abbreviated term meaning “malicious software.”
This is software that is specifically designed to gain access or damage a
computer without the knowledge of the owner. There are various types of malware
including spyware, keyloggers, true viruses, worms, or any type of malicious
code that infiltrates a computer.



The botnet is an example of using good technologies for bad
intentions. A botnet is nothing more than a string of connected computers
coordinated together to perform a task. That can be maintaining a chat room, or
it can be taking control of your computer. Botnets are just one of the many
perils out there on the Internet.



An attack in which someone intercepts and co-opts an active,
established session. IP spoofing is also an attack method by which IP packets
are sent with a false source address, which may try to circumvent firewalls by
adopting the IP address of a trusted source. This fools the firewall into
thinking that the packets from the hacker are actually from a trusted source.
IP spoofing can also be used simply to hide the true origin of an attack.



Trojan Horse hides malware in what appears to be a normal
file. There are a wide variety of Trojan viruses on the Internet landscape that
can perform an array of tasks. Most Trojans are typically aimed at taking
control of a user’s computer, stealing data and inserting more malware on to a
victim’s computer.


against malware

The best protection from malware continues to be the usual advice is to
be careful about what email attachments you open, be cautious when surfing and
stay away from suspicious websites, and install and maintain an updated,
quality antivirus program.


against botnet

Use a firewall when browsing the Internet. This is easy to do with Mac
computers as they come with Firewall software pre-installed. If you’re using a Windows-based
machine, you might need to install third-party software. Don’t visit websites
that are known distributors of malware. One of the things that a full-service
Internet security suite can do is warn you when you’re visiting such sites.


against spoofing

Don’t visit unsafe websites. Most Internet
security suites include a component alerting you that the site you’re about to
visit is unsafe. Don’t download attachments or click on links in unfamiliar
emails. Protect accounts with complex, unique passwords.