CS103 Notes: Start of Semester – First Midterm.
What is a domain name?
A domain name is part of a URL.
o Unique identifier for page, image, or file on the web.
How do domain names work?
IP (Internet Protocol) address distinguishes it from all other devices on the
Domain name= friendly IP equivalent.
TLD: Toplevel Domain
Whatever comes after the dot
o Examples: .com, .edu, .gov, etc.
Twenty percent of the population has a disability.
Before the Internet, blind people had others read newspapers to them. Now, there is
software that will read everything on the computer out loud.
This software is called a screen reader.
Cannot hear videos.
Web builders need to create subtitles or offer transcripts.
2. Motor Impairments
Cannot use hands for keyboard or mouse.
Web builders need to make sites keyboard accessible.
Most common software is called JAWS.
Takes a lot of practice to use
Mac offers “Voice Over” as free alternative. Screen readers identify images, links, lists, and headings.
Security threats involving malware include:
Security threats not involving malware include:
Malware: Software meant to do harm
1. Virus: a parasitic application that can selfreplicate and “lives” in another file.
Example: “Melissa” (1999)
o Carrier: Word document sent by email
o Virus sends itself out to top fifty people in address book
What makes you vulnerable to viruses?
o Not running antivirus software
o Opening unfamiliar email attachments
2. Worm: selfreplicates and can live alone, looks for vulnerabilities in different software.
Example: “Stuxnet” (2011)
o Spread in USB drives
o Copies itself
o Damaged Siemens’ computers by making motors run without notifying
o May have damaged Iran’s nuclear program
What makes your vulnerable to worms?
o Not updating software and operating system
3. Trojan Horse: malware disguised as something useful
Example: Fake antivirus software
o Affects both Macs and Windows
o Tricks you into paying (i.e. steals your money) o May also install malware
What is the purpose of malware?
Makes money, is big busines
Can install spyware to steal your data
Can turn your computer into a “zombie”, part of a botnet, and use it to attack
What is HTML?
Hypertext markup language
What makes a web page?
Start with a plain text file (not Microsoft word)
End the filename with .html
Use HTML to identify the parts of the page
View in web browser
Where can you view a web page?
1. On your computer
You can build an entire web page on your computer
o Only you will be able to see it, however.
2. On your web host
Anything in the publichtml file can be used publically
Tips for working with web host:
o Most web servers run on Unix/Linux
o Unix file names are case sensitive
Do not use spaces
Use only lowercase letters
o Files named “index.html” are special
Internet Security, continued What is the purpose of malware?
Makes your computer part of a botnet
Steals your data
A botnet is a group of computers connected by a “bot”.
Often created to attack websites and send unsolicited emails.
How do botnets work?
A virus or worm infects the computer and installs bot software.
This makes the computer part of a botnet.
User’s computer sends message to “herder” (head of botnet), and awaits
Herder instructs bots to carry out activities.
o Spreading spam
o Click fraud
o Launching denial of service attacks
How can you tell if you are part of a botnet?
If one computer is talking to another at an odd time for no apparent reason.
Botnet activities include:
o Most email providers have spam filters
o If spam is being sent from un“blacklisted” computers, it has a better
chance of getting through
Denial of service attacks
o Attacks/ brings down network by flooding it with useless traffic
o Can be done by groups or individuals
Other Security Risks
Sending an email pretending to be a business/organization in an attempt to
gain confidential information
How to Protect Yourself 1. Install antivirus software
2. Don’t open emails/ email attachments from unknown addresses
What is copyright?
A legal concept that grants artists/authors control over their work for a certain
period of time, and what it can be used for.
Copyright violation ≠ plagiarism
What is the purpose of copyright?
Encourages creativity by allowing authors to profit from their work.
Ensures authors are paid f