COE 201 Lecture 2, Fall 2017

Short Introduction on Networks Internet - Basic Search COE 201- Computer Proficiency Outline • Internet Basics • Web Browser • IP Address • DNS • Protocols • Firewall • Proxy • Search Engines • Search Optimization Internet Basics URL • Uniform Resource Locator • Unique address of any web document/page • Also called domain name or internet address • Is entered in the address bar in your browser To Browse • Or to surf • follow links in a page/ discover websites and their content. • Usually used like "I browse some sites" or "I'm surfing on the net". Downloads • A download is a file you have transferred from another computer to your computer over the internet. Links • Aka Hyperlink • Links one electronic document to another Web Browser • Aka browser • Makes the content on the internet viewable • Converts the data coming from the internet to the graphical interface you see. • Displays all elements of a website at their designated positions. Example: • Internet Explorer (IE) • Mozilla Firefox • Google Chrome • Opera • Safari Web Browser Browser’s basic components: Address Bar:  Most important part of your browser.  You can enter all domain names you want to visit in it. The IP address PC to PC communication Domain Name • Part of URL, between “www.” and the first “/” • In case of http://www.google.com/search... , “google.com” is the domain name. • has a suffix  indicates for what purpose this domain is used. • Every country has also a specific suffix. Because the Internet is based on IP addresses, not domain names, every Web server requires a Domain Name System (DNS) server to translate domain names into IP addresses. The DNS The DNS Domain Name System or Service or Server (DNS) DNS Use .com Commercial (business) .lb Lebanese websites .us U.S. websites .info Informational websites .org Organization .edu Educational organization .gov Government Agency The DNS (continued) Services The DNS (continued) Protocols Protocols (Continued) • Protocols are “languages” that computers use to communicate with each other. • A dialed computer should be able to talk the dialing computer’s protocol. Protocol = Language Typical Protocols Protocol Name Usage HTTP Browsing web pages FTP Downloading/ Uploading files SMTP Sending e-mail POP3 Receiving e-mail Telnet Remote access IRC Chatting Question! What happens from the moment you type an address in your browser window till the moment the page appears? The Firewall Its mission: • Protects your computer(s) or network from the outside attacks. The Proxy With a firewall, no one can get in BUT NO ONE can get out!!! Solution: The proxy is a door in the firewall Firewall Inside Outside Search Engines Three types of search engines: • Human-powered • Crawler Based • Hybrid NOTE: No search engine has more than 40% of the total websites available online!! Search Engines (continued) Human -powered: • Depends on humans for its listings • You submit a short description to the directory for your entire site • A search looks for matches only in the descriptions submitted. • Changing your web pages has no effect on your listing Crawler-Based: • Such as Google • They "crawl" or "spider" the web • create their listings automatically, then people search through what they have found. • you change your web pages they find these changes change your listing. Search Engines (continued) "Hybrid Search Engines" Or Mixed Results • Search engines used to either present: ▫ crawler-based results ▫ human-powered listings. • Today…… both types of results are presented. How to Search? • “+” ▫ To search for two or more terms on the same page. ▫ Type “+” between the terms ▫ Refers to AND ▫ Example: sun + heat • “OR” ▫ To search for either of two (or more) terms on the same page ▫ Type the word OR between the terms ▫ Example: sun OR heat • “-”: ▫ To search for pages that include the first term and not the second ▫ Type “-” between the terms ▫ Example: sun -heat How to Search?(continued) • “” ▫ To search for an exact phrase ▫ Enclose the phrase in quotation marks ▫ Example: “sun heat effects” • ( ) ▫ To group parts of your search ▫ Enclose them in parenthesis ▫ Example: sun + (heat OR burn)  This will return pages with both the words sun and heat or both the words sun and burn. • * ▫ To search for various forms of a word ▫ Add an asterisk to the end of the word ▫ Example: sun*  This returns pages with the words sun, sunglass, sunburn, sunrise… Optimizing your search Let’s try some Google queries: Keywords Results chocolate + cake 93,700,000 chocolate OR cake 1,350,000,000 "chocolate cake" 25,200,000 "cake chocolate" 2,190,000