Networks and the Internet Study Guide

○ Bps bits per second

, the standard measure of data transmission speeds.

4. Draw examples of the following LAN configurations: Ring, Star, Mesh, Bus. Give an advantage or disadvantage of each configuration.

Disadvantages □ Ring - If any of the connections in the network are cut off, all of the network will stop working altogether □ Star - If the central hub stops working, all networks will stop working as well □ Mesh - Only part of the network will stop working if any one of the connections between 2 nodes stop working □ Bus - If the central cable stops working, all network stops working as well

25. Explain the meaning of the following statement in your own words: "The trust model of the Internet involves trade-offs."

Guess: the level of encryption and cryptography determines how secure data is

27. (BTB) Explain the statement: "There are no single points of failure" when referring to the Internet.

If a node in the network stops working, the protocols automatically reroute the message packets around the inoperable link; hence, other nodes will still be working

13. What is steganography? How does it differ from cryptography? (BTB)

Steganography is the art of sending secret messages in imperceptible ways. Cryptography is the art of sending messages that are indecipherable; hence, others are able to tell that there is a hidden message and can become suspicious. Steganography does not arouse suspicion as the coded message is hidden in plain sight.

26. (BTB) What is meant by the Core and Edge when referring to the Internet?

The Core of the Internet is the machines (computers) which make the internet a network. The Edge of the Internet is made of the machines that interface directly with the end users (the computer using the internet)

24. Who owns the Internet?

The internet is not owned by any organization or person

6. List the necessary components of a wireless network. A picture will do just fine.

The necessary components of a wireless network are: 1. Network interface card (NIC) 2. Access Point (AP) 3. Router

3. What is meant by a top-level domain (in a domain name)? Gove two examples.

Top-level domains aka TLS is a term referring to the suffix attached to Internet domain names. § Ex. □ Com - commercial businesses □ Gov - US government agencies □ Edu - educaional institutions such as universities □ Org - organizations □ Mil - military □ Net - network organizations □ Ca - canada □ Th - thailand

16. What is a URL?

URL - aka Uniform Resource Locator; the global address of documents and other resources on the World Wide Web.

7. List and briefly describe 3 (of the many listed) cyber-security tips.

Use and maintain anti-virus software. These softwares will recognize possible threats and protect the computer § Keep software up to date so that attackers will not be able to use their knowledge of known vulnerabilities and problems § Be wary of downloadable files to prevent viruses. Also manually scan the downloaded files.

9. As it relates to the Internet and WWW, what is a Web Crawler or Web spider?

Web crawlers/spiders - A program that automatically fetches Web pages. Spiders are used to feed pages to search engines. It's called a spider because it crawls over the Web. Another term for these programs is webcrawler.

14. What happens to the data in deleted files (files you delete by clicking on the delete key)?(BTB)

When a file is deleted, the index telling the location of the files are deleted; however, the data (file) are still intact unless it is overwritten.

○ Peer-to-peer network aka P2P;

a type of network in which each workstation has equivalent capabilities and responsibilities. This differs from client/server architectures where some computers are dedicated to serving the others. Peer-to-peer networks are generally simpler but they usually do not offer the same performance under heavy loads. The P2P network itself relies on computing power at the ends of a connection rather than from within the network itself.

○ DNS

aka Domain Name System; an Internet service that translates domain names into IP addresses. Because domain names are alphabetic, they're easier to remember. The Internet however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. For example, the domain name www.example.com might translate to 198.105.232.4.

○ IEEE

aka Institute of Electrical and Electronics Engineers (I-triple-E); an organization composed of engineers, scientists, and students. The IEEE is best known for developing standards for the computer and electronics industry.

○ IETF

aka Internet Engineering Task Force; the main standards organization for the Internet. The IETF is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. It is open to any interested individual.

○ IMAP

aka Internet Message Access Protocol; a protocol for retrieving e-mail messages. The latest version, IMAP4, is similar to POP3 but supports some additional features. For example, with IMAP4, you can search through your e-mail messages for keywords while the messages are still on mail server. You can then choose which messages to download to your machine.

○ SMTP

aka Simple Mail Transfer Protocol; a protocol for sending e-mail messages between servers. Most e-mail systems that send mail over the Internet use SMTP to send messages from one server to another; the messages can then be retrieved with an e-mail client using either POP or IMAP. In addition, SMTP is generally used to send messages from a mail client to a mail server. This is why you need to specify both the POP or IMAP server and the SMTP server when you configure your e-mail application.

○ VOIP

aka Voice Over Internet Protocol; a category of hardware and software that enables people to use the Internet as the transmission medium for telephone calls by sending voice data in packets using IP rather than by traditional circuit transmissions of the PSTN.

○ WAN

aka Wide-Area-Network; A computer network that spans a relatively large geographical area. Typically, a WAN consists of two or more local-area networks (LANs).

○ Bluetooth

aka short-range radio technology; aimed at simplifying communications among Internet devices and between devices and the Internet. It also aims to simplify data synchronization between Internet devices and other computers.

○ Protocol

an agreed-upon format for transmitting data between two devices. There are different types and each has its own advantages and disadvantages. § Determines: □ The type of error checking to be used □ Data compression method, if any □ How the sending device will indicate that it has finished sending a message □ How the receiving device will indicate that it has received a message

○ Network interface card (NIC)

an expansion board you insert into a computer so the computer can be connected to a network. Most NICs are designed for a particular type of network, protocol, and media, although some can serve multiple networks

○ Nodes

in networks, a processing location. can be a computer or some other device, such as a printer. has a unique network address, sometimes called a Data Link Control (DLC) address or Media Access Control (MAC) address; in tree structures, a point where two or more lines meet

○ Browser

is a software application used to locate, retrieve and display content on the World Wide Web, including Web pages, images, video and other files. As a client/server model, the browser is the client run on a computer that contacts the Web server and requests information. The Web server sends the information back to the Web browser which displays the results on the computer or other Internet-enabled device that supports a browser.

○ Client

is an application that runs on a personal computer or workstation and relies on a server to perform some operations. For example, an e-mail client is an application that enables you to send and receive e-mail

○ HTML aka HyperText Markup Language;

is the standard markup language used to create web page

○ HTTP

is the underlying protocol used by the World Wide Web. _______ defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands.

○ Search engine

programs that search documents for specified keywords and returns a list of the documents where the keywords were found. A search engine is really a general class of programs, however, the term is often used to specifically describe systems like Google, Bing and Yahoo! Search that enable users to search for documents on the World Wide Web.

○ Mashup

refers to a new breed of Web-based applications created by hackers and programmers (typically on a volunteer basis) to mix at least two different services from disparate, and even competing, Websites.

○ Cybersecurity

refers to the technologies and processes designed to protect computers, networks and data from unauthorized access, vulnerabilities and attacks delivered via the Internet by cyber criminals.

○ Broadband

term used to describe a type of data transmission in which a single medium (wire) can carry several channels at once. Cable TV, for example, uses broadband transmission. In contrast, baseband transmission allows only one signal at a time.

18. Give a brief explanation of the hierarchy of domain name syntax (http://www.cs.rutgers.edu. )- or draw a picture to describe this. `

. - root directory § Edu - top-level domain § Rutgers - domain § Cs - subdomain § Www - host name

○ End-to-end network architecture...

...

23. Go to http://www.whatismyip.com/ . What is your IP? What is the 32-bit binary representation of this IP address?

128.6.37.44

15. Give a brief outline of the history of the Internet by listing the main developments and the dates of those developments.

1965 - Email § 1971 - Internet Email § 1975 - Mailing Lists § 1978 - Bulletin Board Systems (CBBS) § 1979 - Usenet and emoticons § 1982 - Minitel (birth of IMS) § 1990 - World Wide Web § 1997 - Weblogs

21. Name three browsers. Give some comparison (or information) of the three.

3 examples of browsers are Internet Explorer, Mozilla Firefox, and Google Chrome. Microsoft Internet Explorer (MSIE) supports Java, JavaScript, ActiveX, RSS, CSS, and Ajax and offers features like tabbed browsing, private browsing, and built-in malware and phishing protection. Firefox is based on the Mozilla code base and offers customization options and features such as its capability to block pop-op windows, tabbed browsing, privacy and security measures, smart searching, and RSS live bookmarks. Google Chrome combines a minimal design with sophisticated technology to make the Web faster, safer, and easier. Its features include access to favorite pages instantly with thumbnails, desktop shortcuts to launch Web applications, and independently run tabs within the browser to prevent browser crashing.

22. Name three search engines. Give some comparison (or information) of the three.

3 search engines are Google, Bing, and Yahoo

○ Modem aka Modulator-Demodulator

; a device or program that enables a computer to transmit data over, for example, telephone or cable lines by converting the digital data to certain forms

○ URL Uniform Resource Locator

; the global address of documents and other resources on the World Wide Web.

○ FTP aka File Transfer Protocol

; the protocol for exchanging files over the Internet. works in the same way as HTTP for transferring Web pages from a server to a user's browser and SMTP for transferring electronic mail across the Internet in that, like these technologies, uses the Internet's TCP/IP protocols to enable data transfer. is most commonly used to download a file from a server using the Internet or to upload a file to a server (e.g., uploading a Web page file to a server).

8. What is meant by Denial-of-Service Attack?

A Denial of Service attack (DoS attack) is a type of attack on a network that is designed to bring the network to its knees by flooding it with useless traffic.

○ Cookies

A message given to a Web browser by a Web server. The browser stores the message in a text file. The message is then sent back to the server each time the browser requests a page from the server.

1. Define the term network and list three advantages provided by networks.

A network is a group of two or more computer systems linked together. 3 Advantages are 1. the sharing of data with computers, the sharing of peripherals, and lessening the cost for anything that can be shared (prevents from buying one device per computer)

19. What is the Internet Society?

A non-governmental, non-profit organization dedicated to maintaining and enhancing the Internet. They are responsible for developing and approving new Internet standards and protocol

○ Packets

A piece of a message transmitted over a packet-switching network.

○ Web crawlers/spiders

A program that automatically fetches Web pages. Spiders are used to feed pages to search engines. It's called a spider because it crawls over the Web. Another term for these programs is webcrawler.

○ Bandwidth

A range within a band of frequencies or wavelengths; 2. The amount of data that can be transmitted in a fixed amount of time. For digital devices, the bandwidth is usually expressed in bits per second(bps) or bytes per second. For analogdevices, the bandwidth is expressed in cycles per second, or Hertz (Hz).

○ Meta tag

A special HTML tag that provides information about a Web page. Unlike normal HTML tags, meta tags do not affect how the page is displayed. Instead, they provide information such as who created the page, how often it is updated, what the page is about, and which keywords represent the page's content.

○ Hotspot

A specific geographic location in which an access point provides public wireless broadband network services to mobile visitors through a WLAN. Hotspots are often located in heavily populated places such as airports, train stations, libraries, marinas, conventions centers and hotels. Hotspots typically have a short range of access.

20. What is W3 Consortium?

Aka The World Wide Web Consortium (W3C); an international consortium of companies involved with the Internet and the Web. Its purpose is to develop open standards so that the Web evolves in a single direction rather than being splintered among competing factions

5. Describe the process followed by packet switching in transferring data.

Messages/data are first divided into packets. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message.

11. What is a meta tag?

Meta tag - A special HTML tag that provides information about a Web page. Unlike normal HTML tags, meta tags do not affect how the page is displayed. Instead, they provide information such as who created the page, how often it is updated, what the page is about, and which keywords represent the page's content.

12. How can one "forge metadata"? (BTB)

Metadata can be forged by altering the information of the computer, such as resetting it's clock

10. What is metadata?

Metadata is data about data; metadata describes how and when and by whom a particular set of data was collected, and how the data is formatted. It is essential for understanding information stored in data warehouses and has become increasingly important in XML-based Web applications.

○ Asynchronous transmission

Not synchronized; that is, not occurring at predetermined or regular intervals. The term is usually used to describe communications in which data can be transmitted intermittently rather than in a steady stream. For example, a telephone conversation is this because both parties can talk whenever they like

○ Synchronous transmission

Occurring at regular intervals. The opposite of synchronous is asynchronous. Most communication between computers and devices is asynchronous -- it can occur at any time and at irregular intervals. Communication within a computer, however, is usually synchronous and is governed by the microprocessor clock. Signals along the bus, for example, can occur only at specific points in the clock cycle.

17. Give an advantage and a disadvantage of VOIP.

One advantage of VoIP is that the telephone calls over the Internet do not incur a surcharge beyond what the user is paying for Internet access, much in the same way that the user doesn't pay for sending individual emails over the Internet

2. Compare and contrast peer-to-peer networks with client-server networks.

Peer-to-peer network - aka P2P; a type of network in which each workstation has equivalent capabilities and responsibilities. This differs from client/server architectures where some computers are dedicated to serving the others. Peer-to-peer networks are generally simpler but they usually do not offer the same performance under heavy loads. The P2P network itself relies on computing power at the ends of a connection rather than from within the network itself. § Client-server network - a network architecture in which each computer or process on the network is either a client or a server

○ LAN aka Local-Area-Network;

a computer network that spans a relatively small area. Most are confined to a single building or group of buildings. Most connect workstations and personal computers. Each node (individual computer ) in a as its own CPU with which it executes programs, but it also is able to access data and devices anywhere on the . This means that many users can share expensive devices, such as laser printers, as well as data. Users can also use the to communicate with each other, by sending e-mail or engaging in chat sessions.

○ Server

a computer or device on a network that manages network resources. There are many different types of

○ MAN aka Metropolitan Area Network;

a data network designed for a town or city. In terms of geographic breadth, are larger than local-area networks (LANs), but smaller than wide-area networks (WANs). are usually characterized by very high-speed connections using fiber optical cable or other digital media.

○ Router

a device that forwards data packets along networks. It is connected to at least two networks, commonly two LANs or WANs, or a LAN and its ISP's network. Routers are located at gateways, the places where two or more networks connect

○ Internet

a global network connecting millions of computers

○ Client-server network

a network architecture in which each computer or process on the network is either a client or a server

○ IP address aka Internet Protocol address;

an identifier for a computer or device on a TCP/IP network. Networks using the TCP/IP protocol route messages based on the IP address of the destination. specifies the technical format of packets and the addressing scheme for computers to communicate over a network. § Static - A type of NAT in which a private IP address is mapped to a public IP address, where the public address is always the same IP address (i.e., it has a static address). This allows an internal host, such as a Web server, to have an unregistered (private) IP address and still be reachable over the Internet. § Dynamic - A type of NAT in which a private IP address is mapped to a public IP address drawing from a pool of registered (public) IP addresses. Typically, the NAT router in a network will keep a table of registered IP addresses, and when a private IP address requests access to the Internet, the router chooses an IP address from the table that is not at the time being used by another private IP address. Dynamic NAT helps to secure a network as it masks the internal configuration of a private network and makes it difficult for someone outside the network to monitor individual usage patterns. Another advantage of dynamic NAT is that it allows a private network to use private IP addresses that are invalid on the Internet but useful as internal addresses.

○ WWW aka World Wide Web;

an indication that the Web address exists on the vast network of the World Wide Web. Sometimes in a URL the _____ is followed by a number, such as "WWW1" or "WWW2." The number that follows the "____" indicates that the data being retrieved by the Web browser is gathering the information from a different Web server than the one that serves the typical "____" address.

○ Network topology

the shape of a network, or the network's layout. How different nodes in a network are connected to each other and how they communicate are determined by the network's topology. Topologies are either physical or logical. § Bus - all devices are connected to a central cable, called the bus or backbone § Ring - all devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it § Star - All devices are connected to a central hub. Nodes communicate across the network by passing data through the hub. § Mesh - Devices are connected with many redundant interconnections between network nodes § Tree - a hybrid topology. Groups of star-configured networks are connected to a linear bus backbone

○ TCP/IP aka Transmission Control Protocol/Internet Protocol;

the suite of communications protocols used to connect hosts on the Internet. uses several protocols, the two main ones being TCP and IP. TCP/IP is built into the UNIX operating system and is used by the Internet, making it the de facto standard for transmitting data over networks. Even network operating systems that have their own protocols, such as Netware, also supportTCP/IP.

○ Download

to copy data (usually an entire file) from a main source to a peripheral device

○ Wireless networks

to link a group of computers. Because ____ doesn't require costly wiring, the main benefit is that it's generally easier, faster and cheaper to set up. _______ operate using radio frequency (RF) technology, a frequency within the electromagnetic spectrum associated with radio wave propagation.

○ Upload

to transmit data from a computer to a bulletin board service, mainframe, or network

○ Switching techniques

§ Circuit - A type of communications in which a dedicated channel (or circuit) is established for the duration of a transmission. The most ubiquitous circuit-switching network is the telephone system, which links together wire segments to create a single unbroken line for each telephone call. § Packet - Refers to protocols in which messages are divided into packets before they are sent. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message.

○ Host

§ a computer system that is accessed by a user working at a remote location. Typically, the term is used when there are two computer systems connected by modems and telephone lines. The system that contains the data is called the host, while the computer at which the user sits is called the remote terminal § A computer that is connected to a TCP/IP network, including the Internet. Each host has a unique IP address § To provide the infrastructure for a computer service. For example, there are many companies that host files, programs, applications, or even a Web server for companies and individuals. In the case of a Web server, it means that they provide the hardware, software, and communications lines required by the server, but the content on the server may be controlled by someone else

○ DSL/Cable

○ DSL/Cable § DSL - DSL uses a sophisticated modulation scheme to pack data onto copper wires. DSL is sometimes referred to as a last-mile technology because it is used only for connections from a telephone switching station to a home or office, not used between switching stations. DSL is also called an always on connection because it uses existing 2-wire copper telephone line connected to the premise and will not tie up your phone as a dial-up connection does. There is no need to dial in to your ISP as DSL is always on. The two main categories of DSL for home subscribers are called ADSL and SDSL. § Cable - Through the use of a cable modem you can have a broadband Internet connection that is designed to operate over cable TV lines. Cable Internet connections works by using TV channel space for data transmission: certain channels are used for downstream transmission and other channels for upstream transmission. Because the coaxial cable used by cable TV provides much greater bandwidth than telephone lines, a cable and Internet modem can be used to achieve extremely fast access to the Web. This, combined with the fact that millions of homes are already wired for cable TV, has made cable Internet service something cable TV companies have really jumped onboard with.

○ IPv6 and IPv4

○ IPv6 and IPv4 § IPv6 - the successor to Internet Protocol Version 4 (IPv4). It was designed as an evolutionary upgrade to the Internet Protocol and will, in fact, coexist with the older IPv4 for some time. IPv6 is designed to allow the Internet to grow steadily, both in terms of the number of hosts connected and the total amount of data traffic transmitted. § IPv4 - the fourth revision of the Internet Protocol (IP) used to to identify devices on a network through an addressing system. The Internet Protocol is designed for use in interconnected systems of packet-switched computer communication networks

○ SSL/TSL

○ SSL/TSL § SSL - aka Secure Sockets Layer; a protocol developed by Netscape for transmitting private documents via the Internet. SSL uses a cryptographic system that uses two keys to encrypt data − a public key known to everyone and a private or secret key known only to the recipient of the message § TSL -