chpt 13.pdf

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University of Guelph
Computing and Information Science
CIS 1200
John Saville

1 Chapter 13: How the Internet Works THE MANAGEMENT OF THE INTERNET Who owns the Internet?  U.S. government funded it, but no one really owns it Does anyone manage the Internet?  Nonprofit organizations and user groups each with a specialized purpose Who pays for the Internet?  The National Science Foundation (NSF), the primary source of funds is tax dollars  WE DO! INTERNET NETWORKING Connecting to the Internet How are computers connected to the Internet?  Network of networks  Internet backbone is the main paths of the Internet, along which data travels the fastest  Ex, Verizon business, AT&T, Sprint, and Qwest How do ISPs that form the Internet backbone communicate?  A T line (initially) carried data over twisted pair lines  Now-a-days high-speed is connected to a fiber-optic line, designated as an optical carrier (OC) line How are the ISPs connected to each other?  Once known as network access points (NAPs), which were designed to move large amounts of data quickly between networks  Now, data-exchange method is known as an Internet exchange point (IXP), which is made up of one or more network switches  Switches are devices that send data on a specific route through a network How do individuals connect to an ISP?  Point of presence (POP), which is a bank of modems, servers, routers, and switches through which many users can connect to an ISP simultaneously The Network Model of the Internet What type of network model does the Internet use?  Client/server model which client computers request servers and other computers, known as servers, provide those services to the clients  Different types of servers: 1. Web server- computer that runs specialized operating systems 2. Commerce server- computer that hosts software that enables users to purchase goods and services over the web 3. File server- computer that is deployed to provide remote storage space or to act as a storehouse for files that users download Do all Internet connections take place in a client/server mode?  Peer-to-peer (P2P) mode  Ex, BitTorrent  Pieces of the files is called, seeds  A group of users is called a swarm 2 DATA TRANSMISSION AND PROTOCOLS Computer protocol is a set of rules for exchanging electronic information Why were Internet protocols developed?  Open system meaning its design would be made public for access by any interested party  Proprietary system is the private system  Open system protocol allows anyone to use it on their computer and be able to communicate with any other computer using the same protocol Were there problems developing an open system Internet protocol?  Circuit switching has been used since the early days  Circuit switching is when a dedicated connection is formed between two points, and the connection remains active for the duration of the transmission (for telephones)  Computers, on the other hand, process communication is bursts Packet Switching If they cant use circuit switching what do computers use to communicate?  Packet switching is the communications methodology that makes computer communication efficient  With packet switching data is broken into smaller chunks (each one called a packet or a data packet) that are sent over various routes at the same time What information does a packet contain? 1. Address to which the packet is being sent 2. Address from where the packet originates 3. Reassembling instructions 4. The data that is being transmitted Why do packets take different routes, and how do they decide which route to take?  So that the most efficient route is taken TCP/IP What protocol does the Internet use for transmitting data?  The TCP/IP protocol  Named after, Transmission Control Protocol (TCP) and Internet Protocol (IP) Which particular protocol actually sends the information?  The IP IP ADDRESSES AND DOMAIN NAMES IP Addresses What is an IP address?  A unique identification number that defines each computer, service, or other device that connects to the internet  IP addresses must be registered with the Internet Corporation for Assigned Names and Numbers (ICANN) to ensure uniqueness What does an IP address look like?  Looks like,, this is called a dotted decimal number (or dotted quad) 3  Same address in binary forms looks like, 11000101.10101001.01001001.00111111  Each of the four numbers in a dotted decimal number is referred to as an octet  32 positions are available for an IP address (4 octets with 8 positions each)  IP addresses are considered 32-bit numbers Will we ever run out of IP addresses?  Internet Protocol version 4 (IPv4) was used in the past  Classless interdomain routing (CIDR) is now used  CIDR allows a single IP address to represent several unique IP addresses by adding a network prefix, which is a slash and a number, to the end of the last octet Are there other Internet addressing systems?  Internet protocol version 6 (IPv6)  Which makes addresses longer by using 8 groups of 16-bit numbers referred to as, hexadecimal notation: 0000:0000:0000:0000:0000:0000:0000:0000 How does my computer get an IP address?  Static addressing means that the IP address for a computer never changes and is most likely assigned manually by a network administrator or ISP  Dynamic addressing is when your computer is assigned an address from an available pool of IP addresses (more common) How exactly are dynamic addresses assigned?  Handled by dynamic host configuration protocol (DHCP)  DHCP takes a pool of IP addresses and shares them with hosts on the network on an as-needed basis  If you are only logging on to the Internet for some time an IP address may be temporarily assigned to you What are the benefits of dynamic addressing?  More secure by keeping hackers out (IP address changing daily) Domain Names I’ve been on the Internet so why have I never seen IP addresses?  We work with names instead of numbers  Domain name is simply a name that takes the place for an IP address (ex, How are domains organized?  By level  .com is top-level domain (TLD) (anything after the dot)  within top-level domains are second-level domains ( and are two examples) Who controls domain name registration?  ICANN assigns companies or organizations to manage domain name registration DNS Servers How does my computer know the IP address of another computer? 4  URL is converted to IP, and to do this a DNS (domain name system) server is needed (acts as a phonebook)  Default DNS server uses the following steps 1. Requests info from 2. ISP doesn’t know address of so it requests address fro DNS server 3. DNS server doesn’t know server for it either so it queries the root server of the .com domain 4. Root server provides default DNS server with appropriate IP address 5. DNS server stores correct IP address for for future  If IP address is not found in DNS server than root DNS server is used, which knows the location of all the DNS servers that contain the master listings for an entire top-level domain OTHER PROTOCOLS: FTP AND TELNET File Transfer Protocol How does FTP work?  Enables users to share files that reside on local computers with remote computers Can you upload files with FTP?  Yes by either having a browser that handles FTP transfers, or obtaining an FTP client application Telnet What is Telnet?  Is both a protocol for connecting to a remote computer and a TCP/IP service that runs on a remote computer to make it accessible to other computers How do you use Telnet?  Need to know the domain name or IP address of the computer to be connected to using Telnet  Need password and username  On Windows you need to turn on Telnet feature HTTP, HTML, and OTHER WEB JARGON  Web is a grouping of protocols and software that resides on the Internet  Web uses special languages such as HTML and protocols such as HTTP HTTP and SSL Which Internet protocol does a browser use to send requests?  Hypertext transfer protocol (HTTP)  Hypertext documents are documents in which text is linked to other documents or media When the browser sends a request, does it do anything to make the information secure?  Hypertext transfer protocol secure (HTTPS) is a combination of HTTP protocol and network security protocol  This ensures data is sent securely over the Web  Transport layer security (TLS) and the secure sockets layer (SSL) are two protocols that provide data integrity and security for transmissions over the Internet
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