Term
| Why should I care about networks? |
|
Definition
- Computers are more useful to people when they are connected to networks
- When connected to the Internet, you are part of a functioning network of networks containing millions of computers
- Networks allow you to send and receive email, browse web pages stored across the globe, download audio and video files, and even talk to friends using the telephone |
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Term
|
Definition
| When two or more people work together to achieve a common goal, result, or product |
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Term
T or F?
Effective collaboration produces results greater than those that could be produced by any of the individuals working alone |
|
Definition
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Term
| Collaboration involves ___________ and _____________ and often makes use of computer networks |
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Definition
| Coordination and communication |
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Term
| 4 Factors Driving the Effectiveness of a Collaboration |
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Definition
Communication skills and culture
Communication systems (Especially crucial nowadays that group members can be distributed in different areas)
Content management (to ensure conflicts do not occur)
Workflow control |
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Term
|
Definition
The larger the number of people using a network, the more valuable that network becomes
AKA the Network Effect |
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Term
| When networks first start, people look for ____________ |
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Definition
Critical mass: The point at which the value of being part of the network is larger than the cost of being on it
At this point, the network will start to grow very rapidly |
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Term
T or F?
Network growth leads to congestion problems or the market may become saturated |
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Definition
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Term
|
Definition
| A collection of computers that communicate with one another over transmission media |
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Term
|
Definition
The electronic transfer of data
Ex. 2 people on the phone, two people emailing, 2 machines sending info to each other
Occurs through transmission media |
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Term
| 2 types of transmission media |
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Definition
Wireline (physical) - ex. copper cable,s optical fibre cables
Wireless - ex. transmitting light or radio frequencies including cellular and satellite systems |
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Term
| 3 examples of wireline transmission media |
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Definition
Twisted-pair copper (telephone wire)
Coaxial cable (cable television)
Fiber-optic cable |
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Term
| 4 examples of wireless transmission media |
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Definition
- Infrared light
- Cellular telephone (analog or digital)
- Microwave
- Satellite (geostationary or low-earth) |
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Term
|
Definition
The amount of electronic data that can be transferred using
transmission media
Measured in bits per second such as Kbps, Mbps, Gbps |
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Term
| What are the 2 basic ways to send data? |
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Definition
Analog - continuously varying frequency; smooth but inaccurate
Digital - series of bits; (high voltage = 1, low voltage = 0)
accurate and choppy |
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Term
|
Definition
The procedures used to transfer information
between machines
Ensure that the data being sent by one machine, will be recognized by other machines receiving the data
Two machines must agree on the protocol to use, and they must follow that protocol as they send messages back and forth |
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Term
| 3 Basic Types of Computer Networks |
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Definition
Local Area Network (LAN) - computers connected at a single physical site
Wide Area Network (WAN) - computers connected between 2 or more separated sites
Internet - networks of networks |
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Term
|
Definition
- Connects computers within a relatively small, single geographic location
- Two to several hundred computers
- One geographic area only
- Communication lines can be placed where the organization wants |
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Term
| What is the distinguishing feature of LAN? |
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Definition
| It is in a single location |
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Term
T or F?
LANS are designed to share resources between people in different geographical locations. |
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Definition
False: LANs are designed to share resources between people in the same geographical location
Ex. File server for storing shared files
Print sever for sharing a single printer
Application server for sharing applications |
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Term
|
Definition
- Connect computers at different geographical locations (Two or more separated sites)
- Uses communication networks from vendors (Licensed by government)
- No cabling between sites
- Cable connections made through licensed
communications companies |
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Term
|
Definition
- Network of networks
- Connect LANs, WANs, and other internets
- Use a variety of communication methods and conventions (Seamless flow of data provided by layered protocol) |
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Term
| The ___________ is used for emailing and web browsing |
|
Definition
Internet (w/ an upper case I)
Not all internets are the Internet! |
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Term
|
Definition
A special purpose computer that receives and transmits
messages on the LAN |
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Term
| Network Interface Card (NIC) |
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Definition
- Hardware that connects each device’s circuitry to the cable
- Each device on a LAN has one
- Newer machines have an onboard NIC, which is built into the computer - a card that fits into an expansion slot
- Some new laptops may only have support for wireless networks so if you want to connect to a wired network, you need a special adapter |
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Term
|
Definition
- Media Access Control address
- Unique identifier for network interface cards (hardware)
- Never changes |
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Term
| The devices on a LAN are connected through 1 of 2 media |
|
Definition
1) Unshielded twisted pair (UTP) cable
- A device called the RJ-45 connector is used to connect the UTP cable into NIC devices on the LAN
2) Optical fibre cables
- The signals on these cables are light rays reflected inside glass core surrounded by cladding which is wrapped with an outer layer to protect it
- uses ST and SC connectors |
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Term
| IEEE 802.3 (Ethernet) Protocol |
|
Definition
- Specifies hardware characteristics (like which wire carries which signals)
- Describes how messages are packaged
- Determines how messages are processed
- Operates at Layers 1 and 2 of TCP/IP-OSI architecture
- Most personal computers have an onboard NIC that supports 10/100/1000 Ethernet, which allows for Transmission rates of 10, 100, or 1000 Mbps (megabits per second) |
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Term
|
Definition
- A computer network that allows users to connect without using a network cable
- Uses a wireless NIC (WNIC) which connects to an access point that connects users to the wired network |
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Term
| What protocols do NICs and WNICs operate on? |
|
Definition
NICs operate on 802.3 protocol (Ethernet)
WNICs operate on 802.11 protocol (Wi-Fi) |
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Term
| 2 trends for accessing the Internet |
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Definition
- Your computer is likely to be a portable laptop than desktop
- Your new smartphone or other highly portable device such as a tablet are used more frequently to get info on the go |
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Term
|
Definition
| Devices that combine a powerful processor with sophisticated operating systems and cellular network technology to provide a host of applications |
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Term
| Examples of Operating Systems |
|
Definition
BlackBerry OS (RIM)
iPhone OS (Apple)
Windows Mobile
(Microsoft)
Android (Google; open source)
Linux (open source) |
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Term
|
Definition
| Hybrid-type devices that fill a gap between small handheld smartphones and notebook computers |
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Term
|
Definition
- Mobile commerce, enabled by smartphones and mobile devices
- Allows users to conduct new kinds of transactions
Examples: Mobile banking, mobile ticket purchases, mobile coupons |
|
|
Term
|
Definition
3rd generation
A group of standards for wireless communications
Most smartphones operate on it |
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Term
| Difference between 2G and 3G |
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Definition
| 3G provides higher data transfer rates and allows for simultaneous use of voice and data transfer |
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Term
|
Definition
Support
Security
Synchronization complexity
Ownership |
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Term
| The Internet is a __________ |
|
Definition
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Term
| ___________ implement the protocols for WANs |
|
Definition
Routers (special purpose computers that implement protocols for WANs)
Typically connects your computer to computers owned and operated by your Internet service provider (ISP) |
|
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Term
| Internet Service Provider (ISP) |
|
Definition
Provides legitimate Internet address
Serves as gateway to the Internet
Pay for the Internet (collect money from customers and pay access fees/other charges on your behalf) |
|
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Term
|
Definition
Differ in transmission speed...
Narrowband – less then 56 kbps
Broadband – in excess of 256 kbps |
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Term
|
Definition
The last letters in any domain name
Ex. .ca, .com, .org, .biz
Go to ICANN (Internet Corporation for Assigned Names and Numbers) to determine which agencies ICANN has licensed to register domains for each particular TLD |
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Term
|
Definition
Uniform Resource Locator
Easy to remember address on the Internet |
|
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Term
|
Definition
- A numbered address for each machine connected to
the network
- It is a logical address (assigned through software) and not a physical address (such as a MAC on a NIC)
- Public IP addresses are used on the Internet
e.g. SFU IP address is 142.58.102.68
- Private IP addresses are used within private networks and internets |
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Term
|
Definition
Domain Name System (DNS)
Converts human-friendly URLs into computer-friendly IP addresses
It is a distributed Internet directory service |
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Term
|
Definition
- Today, when you plug in your computer to a LAN, a program in your OS will search the network for a DHCP server
- Dynamic Host Configuration Protocol server is a computer or router that hosts a program called DHCP
- DHCP assigns a temporary IP address to your computer
- When you disconnect, the IP address is available again
- The DHCP server re-assigns it when it is needed |
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Term
| What happens when DNS fails? |
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Definition
Web sites cannot be located and email delivery
stalls |
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Term
|
Definition
Conversion of domain name into a public IP address
Done by computers called domain name resolvers
Resolvers reside at ISPs, academic institutions, large companies, government organizations
They keep track of domain name requests and store locations for future use
When a resolver can't find a domain name, it searches for the IP address at a resolver that is at a higher level
Highest-level resolvers tend to be up to date but it can take time for lower level resolvers to get the accurate info |
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Term
| 3 ways to connect home/small biz computers to an ISP |
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Definition
- Through a regular telephone line (Dial-Up)
- Through a special telephone line cBa DSL line
- Through a cable TV line |
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Term
| Before being sent, digital data on a computer needs to be converted to _______ signals, then converted to a ________ signal before the other computer can read it. |
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Definition
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|
Term
| What device converts digital signals to analog signals back to analog during an Internet connection? |
|
Definition
| Modem (AKA modulator/demodulator) |
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|
Term
T or F?
All modems use the same protocols and speeds |
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Definition
| False: Different modems use different protocols and speeds |
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Term
|
Definition
Operate over regular telephone lines
Interfere with voice telephone service
Perform conversion between analog and digital
Connection made by dialing ISP’s phone number
Maximum transmission speed of 56 kbps |
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Term
|
Definition
- (Digital Subscriber Line) modems operate on the
same lines as voice telephones and dial-up modems
- Connection always maintained
- Do not interfere with voice telephone service
- Faster data transmission than dial-up
- Download and upload speeds vary (ADSL vs. SDSL) |
|
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Term
| ADSL vs. SDSL Subscriber Lines |
|
Definition
Asymmetric Digital Subscriber Lines (ADSL)
- DSL lines that have different upload and download speeds
- Used by most homes and small businesses because they receive more data than they transmit and don't need to upload that much data as quickly
Symmetrical Digital Subscriber Lines (SDSL)
- Offer the same fast speed in both directions (as much as 1.544 megabits per second is guaranteed)
- Used by some users and larger businesses |
|
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Term
|
Definition
- Provide high-speed data transmission
- Connection always maintained
- Do not interfere with television transmission
- Use cable television lines
- High-capacity optical fibre cable run to neighborhood
distribution centre
- At this centre, the optical fibre cable connects to regular television cables that run to subscribers' homes/businesses
- Up to 500 user sites can share the distribution centre, so performance varies depending on how many other users are sending and receiving data
- Depending on the configuration, users CAN download data up 5 Mbps and can upload data at 256 kbps |
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|
Term
| How does a Wireless WAN differ from a Wireless LAN? |
|
Definition
Covers a larger area
Use cellular networks to transfer data |
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|
Term
| Describe how Wireless WANs work |
|
Definition
- Portable computer with a wireless WAN modem connects to a base station on the wireless networks via radio waves
- Radio tower carries the signal to a mobile switching centre, where the data are passed on to the appropriate network
- Wireless service provider then provides the connection to the Internet |
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Term
|
Definition
- Done by the Internet Engineering Task Force (IETF)
- Transmission Control Program/Internet Protocol
Layer 1 is used to transmit data within a single network
Layers 2 & 3 are used for data transmission across an internet
Layer 4 provides protocols that help different applications interact with each other and the person using the computer |
|
|
Term
|
Definition
1. Getting Internet Access and Pressing “Send/Receive” - Layer 4, Simple Mail Transfer Protocol (SMTP)
2. Break Apart Message and Get Ready for Transport - Layer 3, Transmission Control Program (TCP)
3. Send and Receive Packets - Layer 2, Internet Protocol (IP) -> the IP's chief purpose is to route messages across an internet. It packages each segment into a packet and places IP data t the front of the packet, the packet then bounces around looking for its destination
4. Reassemble Packets and Display Message - the packets are then sent off to a mail server, the packets are unapcked back into segments and the TCP works to ensure the content of the message is correct
If all the segments are not received, TCP will resend the missing segment |
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|
Term
|
Definition
- Internet Protocol number
- A four byte value that is expressed by
converting each byte into a decimal number (0 to 255)
and separating the bytes with a period (.) |
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Term
| ____ will translate domain name into an IP number |
|
Definition
|
|
Term
|
Definition
Hyper Text Transfer Protocol
The Internet protocol for transferring hypertext files
Handles requests for Uniform Resource Locators (URL) and responses (usually HTML) from the request
Requires the host to use an HTTP server program, and
the viewer to use a HTTP browser |
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Term
|
Definition
| Post Office Protocol (POP) - help us receive mail messages across the web |
|
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Term
|
Definition
| Simple Mail Transfer Protocol (SMTP) - help us to send mail messages across the web |
|
|
Term
T or F?
POP and SMTP often work together to send/receive email. |
|
Definition
|
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Term
|
Definition
| File Transfer Protocol - help us to send files across the network |
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|
Term
|
Definition
- Transmission Control Protocol
- Controls data “packets”
- TCP fragments large HTTP data units; common size is 512 KB and a sequence number added to each TCP data unit
- Responsible for verifying the correct delivery of data from
client to server |
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Term
| Data can get lost in the intermediate network, what can TCP do to help? |
|
Definition
TCP adds support to detect errors or lost data and to trigger
retransmission until the data is correctly and completely received |
|
|
Term
| What does the IP (Internet Protocol) do? |
|
Definition
- IP is responsible for moving packet of data from computer
to computer
- IP carries each message as a collection of packets
- IP forwards each packet based on a four byte destination
address (the IP number)
- IP operates on gateway machines that move data from
department to organization to region and then around the
world |
|
|
Term
| Steps in Packet Switching |
|
Definition
Step 1: Creates packets
- Each message is split into small packets
- A header identifies destination, number of packets, and
packet order
Step 2: “Who’s your daddy” protocol ©
- Each packet takes their own path through the network
- At each node they ask “Are you my daddy?”
- If yes, they are collected, if no they are sent on
Step 3: Re-assembly
- Once all of the packets reach the destination nodes they
are reassembled into the original message |
|
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Term
|
Definition
- Computing device that prevents unauthorized network access
- May be special-purpose computer or program |
|
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Term
|
Definition
- Access Control List
- Encodes rules stating what packets and IP addresses are allowed or prohibited
- Firewalls often have one |
|
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Term
|
Definition
- Perimeter firewalls sit outside organizational network
- Internal firewalls are inside network
- Packet-filtering firewalls examine source address, destination address, and other data before allowing message to pass (this is the simplest type of firewall) |
|
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Term
|
Definition
The process of transforming clear text into coded, unintelligible text for secure storage or
communication |
|
|
Term
|
Definition
| a number used to encrypt data |
|
|
Term
| Coding and decoding messages are done using ______ |
|
Definition
|
|
Term
|
Definition
Symmetric: the same key is used to encode and to decode – simpler and faster
Asymmetric: different keys are used; one encodes the message, and the other decodes the message |
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Term
| Flow of SSL/TLS Encryption |
|
Definition
1. Your computer obtains the public key of the website to which it will connect
2. Your computer generates a key for symmetric encryption
3. Your computer encodes that key using the website’s public key. It sends the encrypted symmetric key to the website
4. The website then decodes the symmetric key using its private key
5. From that point forward, your computer and the website communicate using symmetric encryption |
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Term
|
Definition
- Virtual Private Network
- Additional WAN alternative
- Uses public Internet to create appearance of private connection
- Client and server have point-to-point connection called a tunnel (private pathway over shared network)
- Secure, encrypted communications |
|
|
Term
| What 2 things do web search engines require? |
|
Definition
1. a way to collect URLs
2. a method for storing/accessing the URLs so that they can be searched |
|
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Term
| _______ browse the web to find URLs. |
|
Definition
Web crawlers (AKA web spiders)
They browse the Web in a very methodical way
Start with a list of seed URLs, then visits the URLs and harvest certain bits of info (some crawlers harvest specific info like emails for spam purposes)
The list of URLs created by the crawler can be referred to as the crawl frontier |
|
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Term
|
Definition
Creates indexes for the results from the web crawling
Done by different programs and = organized by a set of rules |
|
|
Term
|
Definition
| - An understanding of breadth of coverage and the ordering of the results from a search |
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Term
| Why is content management important in effective collaboration? |
|
Definition
- When multiple users are contributing, one's work might interfere with another's hence we mst be able to keep track of various versions of work and ensure conflicts do not occur
- Ensures that conflicts are handled correctly
- In some collaborations, members have different rights and privileges - so content management info systems and databases help enforce these restrictions |
|
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Term
|
Definition
- A process or procedure by which content is created, edited, used and disposed of
- Very similar to the idea of a business process
- A business process focuses on delivering a good/service externally to a customer whereas workflow focuses on delivering goods or serves internally to other employees
- Specifies a particular ordering of tasks and includes processes for handling rejected changes/dealing with exceptions |
|
|
Term
T or F?
All four collaboration drivers are equally important for all collaborations |
|
Definition
| False: Different groups will need emphasize different drivers. Ex. ad hoc groups will seldom need formalized workflows - communication in this case may be more important. For engineers, the workflow may be very important |
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Term
| Networks where one can support all users and switching is hard are called _______ |
|
Definition
|
|
Term
|
Definition
- Global positioning system
- Uses dozens of satellites orbiting Earth that transmit precise microwave signals
- GPS receivers calculate their position by measuring the distance between them and other satellites
- With microwave signals from at least 3 satellites, you can compute where you are
- Combining GPS with a map database has enabled the creation of automobile navigation systems (ANSs) which help guide drivers from point A to point B |
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Term
| Why are the wires in UTP cables twisted? |
|
Definition
| The wires in Unshielded Twisted Pair (UTP) cables are twisted because twisting the wires substantially reduces cross-wire signal interference, which occurs when wires run parallel over long distances |
|
|
Term
T or F?
LANs always only use one switch. |
|
Definition
| False: Typically in a building with several floors, a switch is placed on each floor and the computers on that floor are connected to the switch with a UTP cable. The switches on each floor are then connected by a centrally located main switch, which is often located in a communications room. |
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|
Term
| Why do IEEE LAN protocols always start with the numbers 802? |
|
Definition
| The Institute for Electrical and Electronics Engineers (IEEE) sponsors committees that create/publish protocols and other standards. The committee addressing LAN standards is known as the IEEE 802 Committee, hence why protocols start with 802. |
|
|
Term
T or F?
The abbreviations used for communication speeds differ from those used for computer memory. |
|
Definition
True: For communications equipment, k stands for 1000, not 1024 like in memory. M stands for 1 000 000, not 1024 1024 and G stands for 1 000 000 000
THUS 100 Mbps is 100 000 000 bits per second
NOTE: CMNS speeds are expressed in bits, whereas memory sizes are expressed in bytes |
|
|
Term
T or F?
The 802.11g wireless protocol is the fastest wireless protocol there is. |
|
Definition
| False: The 802.11n protocol allows for speeds up to 248 Mbps and is becoming increasingly popular |
|
|
Term
| Generally, how much is the coverage of a wireless access point? |
|
Definition
Typically ranges from 40 to 100m, but depends on many factors including whether the location is indoors or outdoors, teh weather, obstructions, devices that broadcast on a similar frequency and the power output of devices
Devices called repeaters and reflectors are sometimes used to amplify/reflect signals to extend the range |
|
|
Term
T or F?
Access points are able to process messages according to both the 802.3 and the 802.11 standards. |
|
Definition
| True: The AP has to be able to process messages according to both standards because it sends and receives wireless traffic using the 802.11 protocol and then must communicate with the switch using the 802.3 protocol |
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Term
|
Definition
Bring your Own Device (BYOD) approach
Increasingly adopted by organizations - it is a policy that asks employees to bring their own devices for work |
|
|
Term
T or F?
The Web and the Internet are the same thing. |
|
Definition
| False: They are not the same thing. The Web is a subset of the Internet and consists of sites/users that process the HTTP (Hypertext transfer protocol) |
|
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Term
| Programs that implement the HTTP protocol are called ______ |
|
Definition
Browsers
Ex. Firefox and Internet Explorer |
|
|
Term
|
Definition
| The communications infrastructure that supports all application-layer protocols, including the HTTP, the simple mail transfer protocol (SMTP) and the file transfer protocol (FTP) |
|
|
Term
| Public vs. Private iP addresses |
|
Definition
Public IP address
- Used on the internet
- Assigned to ISPs and major institutions in blocks by ICANN
Private IP address
- Used within private networks and internets
- Controlled only by the organization that operates the private network or internet |
|
|
Term
| When 2 devices connected by modems use the same protocols, but different speeds, the ______ speed one is the one at which they operate. |
|
Definition
|
|
Term
T or F?
In most cases, the speed of cable modems and DSL modems is about the same |
|
Definition
|
|
Term
T or F?
A dial-up modem provides broadband access whereas DSL and cable modems provide narrowband access. |
|
Definition
| False: A dial-up modem provides narrowband access and DSL/cable modems provide broadband access. |
|
|
Term
T or F?
Cellular network coverage is generally offered on a nationwide level |
|
Definition
| True: It's usually provided by a wireless service carrier for a monthly usage fee, like a cell description. Someone travelling across the country will be able to access a WAN anywhere there a cell phone receives a signal |
|
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Term
|
Definition
A number that is used to uniquely identify a transaction over a network.
The port number specifies the service provided
Ex. If a person has a network server running web service (HTTP), mail service (SMTP) and file transfer (FTP), then another company wanting to connect to the server must use the port number to indicate which service it wants to communicate with |
|
|
Term
| How can ports be used to create a firewall? |
|
Definition
| For instance, if you do not want anyone outside your intranet to access your web server, you could set up a firewall that prohibits packets destined to Port 80 (the port assigned to your hTTP server) from passing through your routers |
|
|
Term
| Packet filtering firewalls |
|
Definition
- Examine each part of a message and determine whether it should let that part pass
- Examines the soruce address, the destination address and other data to make this decision
- Can prohibit outsiders from starting a session with any user behind the firewall
- Can disallow traffic from particular sites
- Can prohibit traffic from legitimate but unwanted addresses like competitors
- Can filter outbound traffic, keeping employees from accessing specific sites |
|
|
Term
T or F?
Many ISPs provide firewalls for their customers |
|
Definition
| True: By nature, these firewalls are generic and can limit access to ports and IP addresses |
|
|
Term
| What protocol is used by most secure communication over the Internet? |
|
Definition
HTTPS
- With HTTPS, data = encrypted using a protocol called the Secure Socket layer (SSL), AKA the Transport Layer Security (TLS)
- SSL/TLS uses a combination of public key/private key and symmetric encryption |
|
|
Term
| What was the first search engine tool and how did it work? |
|
Definition
Archie - developed in 1990 by Alan Emtage
(Archive with the V)
The program created a searchable database of file names by downloading and storing directory listings of files located on public anonymous FTP sites |
|
|
Term
|
Definition
AKA web spider
A software program that browses the Web in a very methodical way
Starts with a list of seed URLs, then visit the URLs and identifies specific pieces of info
Some crawlers harvest specific things like emails for spam, or hyperlinks and images
Some crawlers even maintain corporate website,s making sure links are still active
The list of URLs made by the crawler = the crawl frontier |
|
|
Term
| Two important considerations when understanding search engines |
|
Definition
1) Breadth of coverage (what percentage of the Web is covered by search engines)
2) The ordering of the results from a search |
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|
