7. Network Communication and Application.pptx

COMPUTER NETWORK AND
COMMUNICATION
Prep. By
E. Leo

TOPICS
COMPUTER NETWORK AND INTERNET
WWW IN COMPUTER NETWORK
ICT APPLICATION
ICT SECURITY

Computer Network and Internet
•Computer network
•Network Components/Devices
•Network Topology
•Types of Network
•Internetwork
•Internet

Introduction
A network is a group of nodes connected by
media/links to communicate and share
resources (s/w or h/w) with each other

Network Nodes
• A node any electronic device capable of
sending, receiving or storing data on the
network
• A network node may be data communication
equipment (DCE) such as a modem, hub or,
switch, Router or data terminal equipment
(DTE) such as two or more computers, Server,
and printers.

Link or Network media
• A link refers to the transmission media connecting two nodes.
• Network media is the actual path over which an electrical
signal/waves travels as it moves from one component to
another.
• It is a physical connection or an interface between the
transmitter and the receiver
• There are two major categories of transmission media,
– Physical(Guided) such as wires or optical fibers
– Wireless (unguided) such as Wi-Fi or Bluetooth
• The network medium is the singular form of network media.

How does a computer network work?
• Nodes and links are the basic building blocks
in computer networking.
• In a working computer network, nodes follow
a set of rules or protocols that define how to
send and receive electronic data via the links.
• The computer network architecture defines
the design of these physical and logical
components.

Computer Network Components
• NIC
• Modem.
• Hub
• Switch
• Router
• Cable

NIC
• NIC stands for network interface card.
• NIC is a hardware component used to connect a
computer with another computer onto a
network
• It can support a transfer rate of 10,100 to 1000
Mb/s.
• The MAC address or physical address is encoded
on the network card chip to identify a network
card uniquely.

Modem
• A modem is a hardware device that allows the
computer to connect to the internet over the
existing telephone line.
• It stands for Modulator/Demodulator.
• It converts the digital data into an analog
signal over the telephone lines.

Hub
• A Hub is a hardware device that divides the
network connection among multiple devices.
• Hub broadcast message or request to the
entire network. All the devices will check
whether the request belongs to them or not. If
not, the request will be dropped.
• The process used by the Hub consumes more
bandwidth and limits the amount of
communication.

Switch
• A switch is a hardware device that connects
multiple devices on a computer network.
• Switch delivers the message to the correct
destination based on the physical address
present in the incoming message.
• Therefore, we can say that switch provides a
direct connection between the source and
destination.

Switch vs. Hub
• A Switch contains more advanced features
than Hub.
• The Switch contains the updated table that
decides where the data is transmitted or not.
• A Switch does not broadcast the message to
the entire network like the Hub.
• It increases the speed of the network.

Router
• A router is a hardware device which is used to
connect a LAN with an internet connection.
• It is used to receive, analyze and forward the
incoming packets to another network.
• A router forwards the packet based on the
information available in the routing table.
• It determines the best path from the available
paths for the transmission of the packet.

Cables and Connectors
• Cable is a transmission media used for
transmitting a signal.
• There are three types of cables used in
transmission:
– Twisted pair cable
– Coaxial cable
– Fibre-optic cable

Network topology
A topology is the arrangement of nodes and
links that make up the network
• They can be configured in different ways to get
different outcomes.

Types of network topologies:
• Bus topology
• Ring topology
• Star topology
• Mesh topology

Bus topology
• Bus topology, all devices share single communication
line or cable.
• Bus topology may have problem while multiple hosts
sending data at the same time.

Ring topology
• Each node is linked to two other nodes,
forming a ring. Data can flow bi-directionally.
However, single node failure can bring down
the entire network.

Star topology
• All hosts in Star topology are connected to a central
device (hub/switch/router) using a point-to-point
connection.
• This topology performs better as data doesn’t have to
go through each node. It is also more reliable.

Mesh topology
• Mesh topology, every node is connected to
every other node in the network.
• A host is connected to one or multiple hosts

7. Network Communication and Application.pptx

PAN(Personal Area Network)
• Personal Area Network is a network arranged
within an individual person, typically within a
range of 10 meters.
• Personal computer devices that are used to
develop the personal area network are the
laptop, mobile phones, media player and play
stations.

LAN(Local Area Network)
• Local Area Network is a group of computers
connected to each other in a small area (up to 1km)
such as school, building, office.
• LAN is used for connecting two or more personal
computers through a communication medium.
• It is less costly as it is built with inexpensive
hardware such as hubs, network adapters, and
Ethernet cables.
• The data is transferred at an extremely faster rate in.
• It is Private Network therefore provides higher
security.

MAN(Metropolitan Area Network)
• MAN, consists of a computer network across an
entire city, college campus or small region
• In MAN, various LANs are connected to each
other to form a larger network.
• It covers a larger geographic area compare to
LAN and it has a higher range than Local Area
Network(LAN).
• A MAN is bigger than LAN but smaller than WAN
extend beyond 100 KM

Uses Of Metropolitan Area Network:
• MAN is used in communication between the
banks in a city.
• It can be used in an Airline Reservation.
• It can be used in a college within a city.
• It can also be used for communication in the
military.

WAN(Wide Area Network)
• A Wide Area Network is a network that extends over a
large geographical area such as
states/countries/continents.
• A Wide Area Network is quite bigger network than the
LAN and MAN.
• A Wide Area Network is not limited to a single
location, but it spans over a large geographical area
through a telephone line, fibre optic cable or satellite
links.
• The internet is one of the biggest WAN in the world.

Different between LAN, MAN and WAN

Internetwork
• An internetwork : two or more computer network
LANs or WAN or computer network segments are
connected and configured by a local addressing
scheme.
OR
An interconnection between public, private,
commercial, industrial, or government computer
networks
• This process is known as internetworking.
• An internetworking uses the internet protocol.

Types Of Internetwork:
• Intranet
• Extranet

Intranet
• It is a private network based on the internet
protocol(i.e. TCP/IP).
• An intranet belongs to an organization which is only
accessible by the organization's employee or
members.
• The main aim of the intranet is to share the
information and resources among the organization
employees.
• An intranet provides the facility to work in groups and
for teleconferences.

Extranet
• It is a communication network based on the
internet protocol (i.e. TCP/IP) used for sharing
information.
• The access to the extranet is restricted to only
those users who have login credentials.
• Allowing non-members such as suppliers and
customers to use company resources.

Introduction
Internet is a global system of interconnected
devices on the networks that use the standard
Internet protocol (TCP/IP) to transmit data
•Internet allows everyone to access all network
resources.
•Internet = International Network.
•TCP-stand for Transmission Control Protocol
•IP-stand for Internet Protocol

Advantage of Internet
• It is cheapest way of communication.
• Fastest way of communication.
• Generalized standard are followed because it
is a public network.
• Best mode of education and business.
• Working with internet is not required very
much skills.

Disadvantage of Internet
• Inadequate security or dangers of hackers and cracker.
• It has much garbage rather than valuable information.
• Sometimes organizational productivity is reduced
because employees are surfing the net for fun rather
than for business purpose.
• Wasting of time because searching & retrieval takes
very much time.
• Addiction provide the harms for body & society both.

Impact of internet

COMMUNICATION
Easily exchange information at any topic by e-mail We can attach
graphics, video, sound and other computer files

EDUCATION
The offers exciting new venues for formal and non- formal teaching and
learning.

BUSINESS
conducting of business activities online, including shopping, investing
and other venture that uses electronic money or electronic data
interchange and also advertise or promote your product

ENTERTAINMENT
Offering an interactive, multimedia experience. Music, videos, sports,
games, chat and more…

Internet as a Tools
We can classified as:
Information search and retrieval tools
through use of search engine and web browser
where we use WWW
Communication tools through use of Email
and now a days social media
Multimedia information tools through use of
online streaming services

Network Protocol
• Network protocols are a set of rules dictates
how to format, transmit and receive data from
servers and routers to endpoints
• It is a digital language in which two devices on
the network must understand in order to
communicate/exchange information with
each other

Types of Network Protocol
• DHCP: Dynamic Host Configuration Protocol
• DNS: Domain Name System protocol
• FTP: File Transfer Protocol
• HTTP: Hyper Text Transfer Protocol
• SMTP: Simple Mail Transfer Protocol
• TCP: Transmission Control Protocol
• UDP: User Datagram Protocol
• IP: Internet Protocol
• ARP: Address Resolution Protocol

DHCP
• DHCP-Dynamic Host Configuration Protocol
• Every device connecting to the internet
requires a unique IP.
• DHCP is a communication protocol that
enables network administrators to automate
the assignment of IP addresses in a network.

DNS
• DNS-Domain Name System Protocol
• The DNS protocol helps in translating or
mapping host names to IP addresses.
• Hosts are identified based on their IP
addresses
• IPs are dynamic but also to memorizing an IP
address is difficult due to its complexity.

FTP
• FTP: File Transfer Protocol
• File Transfer Protocol enables file sharing
between hosts, both local and remote, and
runs on top of TCP.
• For file transfer, FTP creates two TCP
connections: control Information and data
connection.

HTTP
• HTTP: Hyper Text Transfer Protocol
• Http is application layer protocol used to
defines how messages are formatted and
transmitted on the web and what actions
Web servers should take in response to
various commands/request from web
browsers(client)

SMTP
• SMTP: Simple Mail Transfer Protocol
• SMTP is a protocol designed to transfer
electronic mail reliably and efficiently.
• SMTP is a push protocol and is used to send
the email, whereas POP(Post Office Protocol)
and IMAP(Internet Message Access Protocol)
are used to retrieve emails on the end user's
side.

TCP
• TCP: Transmission Control Protocol
• TCP is a transport layer connection-oriented
protocol that provides a reliable stream
delivery and virtual connection service to
applications through the use of sequenced
acknowledgement and flow control.
• TCP provides extensive error checking.

UDP
• UDP: User Datagram Protocol
• UDP is a connection-less transport layer protocol that
provides a simple and faster but unreliable message
service
• It’s an alternative to the transmission control protocol
(TCP)
• Used across the Internet for time-sensitive
transmissions such as video streaming and gaming
• Retransmission of lost data packets isn't possible with
UDP.

IP
• IP: Internet Protocol
• IP is a network layer protocol that contains
addressing and control information, which
helps packets be routed in a network.
• IP works in tandem with TCP, where by IP is
only responsible for delivering the packets and
TCP helps puts them back in the right order.
• IP is designed explicitly as addressing protocol

IP cont……(IP Address)
• The term IP address alludes to the Internet
Protocol address. Example of IP Address:
172.168.1.1
• IP address is used to identify a specific device
in a network for communication.
• Each address comprised of two major parts:
the network number and host number

ARP
• ARP: Address Resolution Protocol
• The Address Resolution Protocol helps map IP
addresses (Logical Address) to physical
machine addresses (MAC address) recognized
in the local network.

World wide Web(WWW) in
Computer Network

WWW
•Terminology
Domain
URL
Hyperlink
Hypertext
HTML
HTTP
•Web pages and Website
•Web Browser(client) and Web Server
•Search Engine

WWW
• World Wide Web is a collection of
documents(web pages) and other web
resources stored in web server which are
identified by URLs, interlinked by hypertext
links, and can be accessed and searched by
web browsers via the Internet.
• World Wide Web is also known as a Web

How it started? (Invention)
• The World Wide Web was invented by a British scientist,
Tim Berners-Lee in 1989
• At the time Internet and Hypertext were available but no
one thought how to use the internet to link or share one
document to another.
• Tim focused on three main technologies that could make
computers understand each other, HTML, URL, and HTTP.
• So, the objective behind the invention of WWW was to
combine recent computer technologies, data networks,
and hypertext into a user-friendly information system.

Difference btn WWW and Internet
• Some people use the terms 'internet' and 'World
Wide Web' interchangeably but it is wrong
• Internet:
– It is a worldwide network of devices
– It enables users to send emails to other users and
chat with them online
• WWW
– It is a network of servers over the internet. User
opened a website like google.com for information

What do I need to access the web?
There are a few items required to access the web:
Computer (PC or Laptop) — if you are buying a computer make
sure that it can be connected to a internet.
Internet Connection—provided by an ISP (Internet Service
provider) through a piece of hardware device known as a modem
and you will create a connection from your PC to this device to get
your internet connection.
Web browser — once you have an internet connection then
you’ll need to have an internet browser on your computer. This
browser allows you to browse websites.

Why is the web so important?
• The world wide web opened up the internet
to everyone
• It connected the world in a way that was not
possible before and made it much easier for
people to get information, share and
communicate.
• It allowed people to share their work and
thoughts

web page
• A web page is a simple document written in
HTML format
• It is a representation of a document that is
actually located at a remote site
• A web page can contain any type of information
e.g. text, sound, pictures, gif, video etc.

How to open a web page
To view a web page, It requires a web browser
where by user enter the web address/URL
into the browser to access the web page
which spread over several web server
through use of internet. In Web page You
can easily navigate between two or more
web pages that are linked through
hyperlinks.

HTML
• HTML: HyperText Markup Language
• HTML is a standard markup language which is
used for creating web pages.
• It describes the structure of web pages through
HTML elements or tags.
• You don't see HTML tags when you open a
webpage as browsers don't display the tags and
use them only to render the content of a web
page.

HyperText
• Hypertext is text which contains links to other
texts that the reader can immediately access.
• It is text that links to other information
• Though hypertext is usually associated with
Web but it has been around since 1960.

Web Address
• A Web Address is a unique address that
identifies a website.
• It is unique address to each sites
• Example: www. Amazon.com
• Generally your browser will recognize the
proper URL when you type in a web address.

URL
• URL: Uniform Resource Locater
• The URL is a standard for specifying any kind
of information on the Internet.
• It is the complete web address of a particular
website available on the Web.
• URL standard naming convention for
addressing documents on internet

URL cont….
Example http://www.Amazon.com
Protocol e.g. http
service available on the Internet e.g. www
Domain name or location e.g. Amazon
Domain level e.g. .com

Domain name
• A domain name (or just a domain) is the
name of a website on the internet
• It’s what comes after “www.” in a web address
or after “@” in an email address.

Domain Level
• Two Types:
commercial
Examples: .com, .net, .biz
non-commercial
Examples: .edu, .mil, .gov

Website
 Website: A group or a collection series of related
web pages(documents that are accessed through
the Internet)
 A website can consist of one page, or tens of
thousands of pages, depending on what the site
owner is trying to accomplish.

Why Do People Visit Websites?
Generally, people look at websites for two primary reasons:
1. They are looking for information
Perhaps they have your business card or have been referred to
you, and they want to read more about your company and what
you do
2.To complete a task.
Visitors may want to buy the latest best seller, download a
software program, or participate in an online discussion about a
favorite hobby.
3. They want to contact you
Go to a company website to look for their telephone number, an
email address or a form you can use to get in touch with them?

Web browser
A web browser (or just Browser) is a software
program that allows a user to locate, access,
and display web pages
We can use a web browser to access content
published on a web server
Browsers are used primarily for displaying and
accessing websites on the internet, as well as
other content

How Browsers work?
whole process takes place in these three steps:
1.Contact to DNS Server,
2.Contact to Server and
3.Rendering

Common web browser
• Internet Explorer(from Microsoft)
• Safari(from Apple)
• Google Chrome(from Google)
• Firefox(from Mozilla)
• Opera

Web Server
• A server is a computer designed to process
requests and deliver data to another
computer over the internet or a local network.
• A web Server is one of the type of server
which host one or more website and access
them through web browser.

Other Common Types of Servers
• Mail server: Email servers facilitate the sending and
receiving of email messages.
• Application Server: Also known as middleware, it
commonly used to connect between database
servers and the end user
• Proxy Server: It acts as a mediator between a client
program and an external server to filter requests
NB: However, there are several types of servers,
including local ones like file servers that store data
within an intranet network.

Search Engine
• A search engine is a tool or program that
allows a user to enter keywords and retrieve
information from the billions stored
information on world wide web or web pages
• A search engine is a special kind of website
that helps users find web pages from other
websites.

Each search engine has its own catalog or
database of collected WebPages, so when an
user requests information from a search engine
It searches and display the results/hits to user.
A true search engine is an automated
software program that moves around the Web
collecting WebPages to include in its catalog or
database.

Common search Engine
• There are a variety of search engines but the
most widely used one is
• Google’s
• Bing
• Yahoo
• Ask
• Yandex
• DuckDuckGo

Health Search Engines

Health professionals and researchers need information from
reputable internet sources to accomplish their research work and
patient care.

Health information searcher has several unique requirements
that distinguish itself from traditional Web search.

Unfortunately, the Web has a large number of documents that
are irrelevant to their work

Hence, search results provided by existing Health Web search
engines often contain much semantic redundancy, which cannot
be easily handled by existing methods for identifying near
duplicate documents or result diversification.

Common Health Search Engines
WebMD is a great one-stop medical information site.
WebMD also has a lot of interesting interactive calculators,
quizzes and other fun stuff that helps you understand
medical information a bit easier (http://www.webmd.com).
PubMed - The National Institutes of Health now offer free
access to MEDLINE®, the best-known database of medical
literature. Full-text of the articles abstracted here can be
ordered from local medical libraries (
http://www.pubmed.gov).
WHO:-An International health authority (
http://www.who.int).

How search engine works
Search Engines do not really search the World Wide Web
directly.
Each one searches a database full text of web pages
selected from the billions of web pages which reside on
servers.
When we search the web using a search engine, you are
always searching a somewhat stale copy of the real web
page.
When you click on links provided in a search engine's
search results, you retrieve from the server the current
version of the page

The Three Parts of a Search Engine
• Spider, crawler or robot: It reads the web pages it finds and follows
the links further down into the website.
• Index, catalog or database: This index contains a copy of each page
that was collected by the spider.
• Search engine software: Go through all the indexed pages to find
matching keywords, then returns the results/hits to the user.

Topics
• E-mail
• E-commerce
• E-Learning
• E-Government
• Online Banking
• Online Shopping
• Online Database

Introduction

E-mail, short for Electronic Mail, it is a modern way sending
and receiving message electronically over the internet.

Email is one of the fundamental internet technologies, a tool
used by nearly every person with an internet connection.

E-Mail originated in the early 1970s by ARPANET and now it is
primary method of communication.

There are many different email services available that allow
you to create an email account and send and receive email and
attachments, many of which are free such as Gmail, hotmail,
yahoo mail etc.

Introduction

An email is a letter that is sent over a computer network instead of being sent
through the post.

You can attach documents and photos to emails, just like you can include a
photo or a document with a letter. You can also attach computer files, such as
programs and spreadsheets.

Sending and receiving email is generally free, and you can actually send an email
to as many people as you like. Each person on email has a unique email address,
which is how you direct an email address to a specific person.
You can even send emails to yourself. This sounds kind of silly, but people do this
to send themselves reminders and also to transfer files from one place to another.
All your emails come into your Inbox, which is like your virtual letter box.

Working with E-mail
How does it do it?
– Our message travels from the computer we send it from over
cables, wires, or wireless means to a Server. The Server acts as a
Post Office, verifying addresses, sorting, and sends out our message
over the internet. Once on the internet, our message travels as data
“packets” to the addressee’s email Server. The addressee’s email
server assembles all the data packets and delivers it to correct
“inbox”.
How does it go to the correct address?
– Each email address is unique. There are 3 parts to an email
address. The “User ID”, “@”, “email client name”. A complete
email address example would be: browne.clickbi@gmail.com

Advantage of E-Mail
Cheapest and fastest way to communication.
Irrespective of location.
Exchange endless amount of data/information.
Global communication is easier and instant.
24 hours service.
Disadvantage of E-Mail
Unsecured communication.
Privacy problem.
Network conjunction.
Power problem.

E-mail Operations
1. Creating Email Account
Open www.gmail.com
click create an account.
Fill your details here and
click Next Step.

Basic component of E-Mail
Compose mail/Write new mail
Inbox
Draft
Trash
Address book/Contact
Spam
Setting

2. Sending and Receiving Emails
To send an email you will first need to create
or compose an email message.
If you click on the compose message link
( new message link ) a new message form
opens.


Email Address fields - These appear normally right at the top of the message form

FROM – Not normally visible unless you have multiple email accounts and
addresses configured. Defaults to your default email address.

TO -You need to enter the email address of the recipient in the to field. You can
enter multiple email addresses usually using a comma to separate them. You can
also use the contacts list or address book to add addresses and most email clients
will automatically suggest email addresses and names as you type.
Note: Names only appear if they are in your address book(contacts list).

CC- CC stands for carbon copy : Anyone listed here will get a copy of the
message and anyone who receives the message will know who else the message
was sent to. Not normally visible

BCC- Blind carbon copy: Anyone listed here will get a copy of the message but
anyone who receives the message will not know that the person(s) on the Bcc line
were sent the message.-Not normally visible It is recommended that you always
use the bcc field when sending messages to confidential mailing lists.


Subject Field – This should contain a brief summary of the content and should
always be used, but is not mandatory. If you leave this field blank then some email
systems may reject the message as spam.

Content Field- This contains the main email message and if you are using HTML
email (default) it can contain text and images. You can leave this field blank.

Adding Attachments - Attachments are files like documents and pictures that you
can include with your email. To add an attachment look for the paper clip icon. All
email providers limit the size of attachments with the standard being around
25MBytes.

Sending The Email - When you click send the email is normally sent immediately
and cannot be cancelled or retrieved. A copy of the email is placed in the sent
items folder.

Receiving and Reading Emails - Your mailbox is divided into a number of folders
and incoming email is normally placed in your inbox. Most email clients display a
list of emails showing the sender and subject with unread
emails shown in bold .

Replying To and Forwarding Email
Most email clients display three icon:
1. Reply to – Send Reply to sender only
2. Reply to all – Send Reply to sender and all
other recipients of the original email
3. Forward – send a copy of the email to new
recipient(s)

Topics
•Malicious Program (Computer Virus)
•Information Security
•Physical security
•Privacy and Identity theft

introduction

A computer virus is a program or piece of code designed
to damage your computer by corrupting system files, resources or
destroying data

Not every piece of code that attacks your PC is a virus.
Computer viruses are just one kind of malware (malicious
software).

Viruses are unique from other forms of malware in that they
are self-replicate by copying itself to another program/files/other
computers without a user's consent. Knowingly or unknowingly
the virus can be spread the infection without the knowledge or
permission of a user or system administrator.

Other kinds of malware:

Trojans: this embedded in message or file and to trick the user to open up
the gates for other malware to infect a PC.

Spyware: this kind of malware designed to spy on users, save their
passwords, credit card details, other personal data and online behavior
patterns, and send them off to whoever programmed it.

Worms: this malware type targets entire networks of devices, hopping from
PC to PC.
 Ransomware: this malware variety hijacks files, encrypts them, and
demands money from its victim in exchange for a decryption key (which may
or may not work, but it probably won’t).

Adware: this malware floods victims with unwanted ads, and opens up
vulnerable security spots for other malware to wiggle its way in.

Types Of Computer Viruses
1. Boot Sector Virus.
Boot virus or boot sector virus alters the boot sector
program stored in the hard disk or any other storage
device such as floppy disks. It replaces the boot sector
program with its own malicious version.
2. Resident Virus.
The resident virus stays permanently in the primary
memory (RAM) of the computer. When you start the
computer, it becomes active and corrupts the files and
programs running on the computer.

3. Direct Action Virus.
This virus comes into action after you have
executed the file. The load is delivered to your
computer and the virus becomes active but It takes
no action unless the file which is infected gets
implemented again.
4. Polymorphic Virus.
It creates its thousands of copies itself; in each
copy, it changes the sequence and byte values to
evade detection by antivirus software. Even the
best antiviruses may not be able to detect this
virus.

5. Macro Virus.
Macro virus alters or infects the macros of a document
or data file. It is embedded as a macro in a document
and adds its codes to the macros of the document. The
virus spreads when infected documents or data files
are opened in other computers..
6. Cavity Virus
It is also known as a spacefiller virus. As the name
suggests, this virus tends to install itself by occupying
the empty sections of a file. It is not easy to detect this
virus as it fills the empty spaces without changing the
size of the file

How do computer viruses spread?
Ways Computer Viruses Are Spread
1. Email attachments.
2. Rogue Websites.
3. Networks.
4. Internet file download
5. Instant Messaging.
6. Phishing Schemes.
7. Infected Software.
8. Hackers.
9. Infected Boot disks.
10. Fake Anti-Virus Software.
11. Mobile Devices.
12. Friends and Relatives removable devices.
13. Social media links

How to protect against computer viruses?
Ant–virus software
running continuous automatic silent antivirus
updates
Don't download files from unknown sources
Scan all new files with virus-scanning software
before opening.
Don't download attachments unless they're
from someone you know.

How do I know if a computer is affected
•You are not able to open a particular document
•The label on a hard drive has changed
•Hardware problems along with strange beeping sound
•no screen display
•Some file turn into shortcuts or different format
•Your computer is running slower than normal
•Strange/ unusual/ error messages
•New and unusual icons suddenly appear on your desktop
•Strange music or sounds suddenly play from the speakers
•Pop-up Dialogue box
•Network/internet issue
•Unknown program run on background

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