Types of Transmission Media

Transmission media is the way to take any information from sender to receiver. They use difference kinds of cables and waves in order to send the information. Data is send through electrical or electromagnetic signals.

Transmission media can be called as ” Communication channel”. An electrical signal in form of present time. An electromagnetic signal is series of electromagnetic energy pulses at various frequencies. These signals can be sent to the copper wires, optical, fibers, atmosphere, water and vacuum. Moreover, Different media have different properties like bandwidth , delay, cost and ease of installation and maintenance.

Types of Transmission Media

– Wired or Guided Media or Bound Transmission Media

– Wireless or Unguided Media or Unbound Transmission Media

 

The data transmission capabilities of various Medias vary differently depending upon the various factors.

– Bandwidth

– Radiation

– Noise Absorption

– Attenuation

 

You can see on this picture :

 

References

http://ecomputernotes.com/computernetworkingnotes/communication-networks/what-is-transmission-media-and-types-of-transmission-media

http://thetechnology4u.blogspot.com/2008/11/wireless-transmission-media.html

 

Network Cable

Differences between LAN and WAN

                            

LAN and WAN, both are the computer networks that using in different size of area. There are some differences between those two networks.

Firstly,the LAN or Local Area Network is covering just only the small area such like home users, office or other department. It is limited for just the small area. In the other hand, WAN can be using to cover the wider area as it named “Wide Area Network”. From the fact that they cover different size of area, so LAN can actually boost the speed up to 1000 mbps while WAN which has to cover larger area can only run the speed at 150 mbps. Moreover, the LAN have higher data transfer rate when comparing with WAN. Plus, LAN has less transmission error. It is also different in the way that LAN can be own by the private sector or single person but WAN is for the over long distance distributed.

The other thing is that LAN need high cost to set up but less cost of maintenance because it is cover just in a small area. while WAN can also be at very high cost too because the remote areas need to be set up, however, it can be incredibly cheap by using software instead but still high maintenance cost as it need to cover the larger area and it is harder to taking care of.

References

http://www.diffen.com/difference/LAN_vs_WAN

http://www.differencebetween.info/difference-between-lan-and-wan

Social Networking sites

     A phrase that is used to describe websites like Facebook,Twitter,and etc where people socially communicate. By chatting, posting on wall, etc. It connects people with friendships, common interests, and things like that. You pretty much have the network theory, and social relationships combined into one

– Advantages of social networking sites

• Get in touch easily ( No need to find places to meet each other )
• Keep in touch with family ( Family can comment and understand posts that are about daily experience and some events 
• Professional networking ( Academics find other scholars to share research or ideas )
•  Staying informed about the world ( People can update their experiences, interests, and news )

Some famous social networking sites

•  Facebook ( http://www.facebook.com/ )
• Twitter ( https://twitter.com/ )
•  Instagram ( http://instagram.com/)

References

http://www.webopedia.com/TERM/S/social_networking_site.html

http://smallbusiness.chron.com/advantages-social-network-sites-32069.html

http://www.ebizmba.com/articles/social-networking-websites

EMAIL

Email, or electronic mail is text messages that can keep files, images or other attachments send through internet to a specified individual or group of individuals. The first email was sent by Ray Tomlinson who developed The “@” sign to separate the user and the machine.

Benefit of email

• Email is fast, we can send any information from anywhere in the world, which means we do not have to wait for a long time to contract with other people. We just type what we want or attach files, so the delay of information between people will disappear automatically.
• Email is cheap, we have to pay for internet cost, after that we do not have to pay anymore compared to sending letters, sometimes they are more expensive than internet
• Easy to use, we do not have to learn a lot for using email to send or receive messages. If we use for many times, we will access quickly and easily
• Email is environmentally friendly, because email offsets some of the damage by reducing the environmental cost of contact. We can save our world by sending email instead of sending letters to someone.

References

http://www.time-management-success.com/advantages-and-disadvantages-of-email.html

http://www.ehow.com/about_4740742_benefits-of-email.html

Virus, Worm, and Trojan horse !!!

What Is a Virus?

A Computer virus that come with file or program which it can spread from one computer to another computer, leaving infection as it travels. some virus can variously annoy computer while other can damage your hardware, software or file  Almost all viruses are attached to an executable file, which mean virus may already exist in your computer, but virus not start damaging anythings unless you run or open a file. Virus cannot spread  without human action.

What Is a Worm?

Worm consider to be a sub-class of virus because it  is similar to virus by design. Worm also spread from one computer to another computer, but unlike virus,  it has the capability to travel without any human action. The biggest danger of worm is its capability to replicate itself on your system. Computer not only sent out a single worm, but it could sent out  hundreds or thousands of copies of itself, creating a huge devastating effect.

What Is a Trojan horse?

Trojan horse is named after the wooden horse the Greeks used to infiltrate Troy. At first, it seem to be useful to your software, but it will damage your computer once you installed or run on your computer. When trojan horse is installed to your computer, the result can vary annoying your computer rather than malicious.

Reference

http://www.webopedia.com/DidYouKnow/Internet/2004/virus.asp

http://www.cisco.com/web/about/security/intelligence/virus-worm-diffs.html

Three Types of Search tools

1. Crawler-based search engines

Crawler-based search engines ( Google, Yahoo, Bing ), Those web sites are creating the list of information that we are searching.

1. – The web server will send the query to the server. the context in the server is almost the same with the server in the back of the book. It will show you the words that match with the query
2. -the doc server will get the query and the information will explain each search result.
3. -lastly, the search results will send back to the user in a second.

2. Human-Powered directories

Human-powered directory, the quality of this kind of search tools are depend on the humans for its listins. the writer will submit the information. It is include to the directory for the entire site.Descriptions submitted is the only thing that the search looks for matches, so changing web pages has no effect on how the writer are listed.

the way to improve a listing in a directory is that they must have a good content because the techniques has nothing to improve a listing in a directory. It might be better to get a review for free than a poor site.

3. Mega-search engines

Mega-search engines, such as Mamma, Metacrawler and Dogpile. Mega-search engines, it is good for saving the time because it is better to use this option in one place and sparing the need to use and learn several seperate search engines. It will be better to use to find hits on obcure items or something that can be found by using the internet

References

1. http://www.yuanlei.com/studies/articles/is567-searchengine/page2.htm

2.http://threes.com/index.php?option=com_content&view=article&id=2560:three-types-of-search-engines-&catid=68:business-economics&Itemid=47

History of the internet