networks

Assignments

 * Modem questions
 * Bitesize test, what is a netwok

Homework

 * Pros/cons of networks (due 25 march)

Connecting to internet.
 * Notes:**
 * Dial-up Internet access** is a form of internet access that uses the facilities of the public switched telephone network (PSTN) to establish a dialed connection to an Internet service provider (ISP) via telephone lines


 * SDN Connection** is one of the most widely used wired Internet options in the global market. ISDN connection is the abbreviated version of Integrated Service Digital Network. The data service of ISDN Connection is similar to that of ordinary telephone connection. ISDN Connection comes with cutting-edge technology.


 * ADSL ** connections work by splitting your phone line into two separate channels, one for data (internet) and one for voice (phone calls), which means you can talk on the phone and be connected to the internet at the same time.

//Usernames and Passwords//
//An issue with computers attached to each other forming a network is stopping other people from accessing your work (securing your files)// //To take care of this problem we use **USERIDs** and **PASSWORDS**// The user id is a unique name or code that identifies you as a member of a computer network. It is necessary so the system knows who you are, and what files it should let you see. Passwords are a code that together with a userid allows the computer to be sure of the identity of the person accessing the information


 * Assignments:**

What is a modem? Is a device that converts the digital signals from a computer into analogue signals that can be sent down a phone line.

What is its purpose? That you can connect to the internet.

=Test Bite= You scored 10 out of 13 1. What does a computer network allow computers to share? You said: resources **Correct**. A computer network allows computers to share **resources**. 2. What does LAN stand for? You said: Local Area Network **Correct**. LAN stands for **L**ocal **A**rea **N**etwork. 3. What does WAN stand for? You said: Wide Area Network **Correct**. Well done. WAN stands for **W**ide **A**rea **N**etwork. 4. To log onto a network, what do you usually need? You said: a user ID and password **Correct**. Well done. In order to log onto a network you usually need **a user ID and password**. 5. Which of the following statements about a network is FALSE? You said: files cannot be shared between users **Correct**. Files **can** be shared between users in a computer network. 6. Which of these statements is TRUE about a LAN? You said: a LAN connects computers in a small area such as an office **Correct**. **A LAN connects computers in a small area such as an office**. 7. What is a server in a computer network? You said: a powerful computer that provides a service, such as centralised file storage **Correct**. **A powerful computer that provides a service, such as centralised file storage**. 8. Which of the following networks is LEAST likely to be a WAN? You said: a school network **Correct**. A **school network** is least likely to be a WAN. 9. What are the three main network topologies? You said: bus, ring, star **Correct**. The three main network topologies are **bus, ring and star**. 10. Which type of network needs 'terminators' to function correctly? You said: ring **Incorrect**. A **bus** network needs 'terminators' to function correctly. 11. Which type of network needs a 'hub' or 'switch'? You said: bus **Incorrect**. A **star** network needs a 'hub' or 'switch'. 12. What is a workstation? You said: another name for a hub **Incorrect**. A workstation is **a computer connected to a network**. 13. What is a data collision? You said: when two devices on a network transmit data at the same time **Correct**. A data collision is **when two devices on a network transmit data at the same time**.

Custom networks. ** Dear Mr. Coxon ** ** A group of students from the school council have decided to set up a proposal with the aim of improving the computer facilities in our school. ** ** We´ve been thinking about using the money we raised in the bake sale last Friday to create a network that could bring lots of new facilities for the school. **** First of all it would be easier if you had conscience of a technical definition of what a network really is : “ a collection of computers that allows users to share resources. ** ** o we have researched and found some information of our current situation in the school. As you of course, already know we have two different building and with them two different sites in each of them there are fifteen stand-alone computers that have access to internet, but with individual routers in each sites. **** Secondly, as we’ve already mentioned a computer network is a number of computers linked together to allow them to share resources like data, media... A network always needs to have a server, various workstations which are computer connected to a network, a printer server which is a software application that manages print requests, a file server which is a networked computer that provides large amounts of shared storage that can be accessed by workstations in the same computer, a hub or a switch which are devices used to connect computers and other network capable devices together to form a network; and various cables to interconnect the computers. In addition we wanted to say that to set up this network firstly we need to look for the type of network that it is more suitable for the current situation in our school, which probably is the bus network as it is the easiest one to install and the cheaper. There are three main types of networks: Firstly, the star network where each device on the network has its own cable that connects to a switch or hub. A hub sends every packet of data to every device, whereas a switch only sends a packet of data to the destination device. Secondly, the ring network where each device (workstation, server, printer) is connected to two other devices, this forms a ring for the signals to travel around. Each packet of data on the network travels in one direction and each device receives each packet in turn until the destination device receives it. Thirdly, the bus network where all the workstations, servers and printers are joined to one cable (the bus). At each end of the cable a terminator is fitted to stop signals reflecting back down the bus. In general a network has lot of advantages that could benefit our school like the following: · The possibility it supplies us of sharing devices such as printers saves money. · Site licences are likely to be cheaper than buying several standalone licences. · Files can easily be shared between users. · Network users can communicate by email and instant messenger. · Security is good - users cannot see other users' files unlike on stand-alone machines. · Data is easy to backup as all the data is stored on the file server. However we need to be fair and say that networks have also some disadvantages that could affect us:

▪Purchasing the network cabling and file servers can be expensive. ▪Managing a large network is complicated, requires training and a network manager usually needs to be employed. ▪If the file server breaks down the files on the file server become inaccessible. ▪Email might still work if it is on a separate server. The computers can still be used but are isolated. ▪Viruses can spread to other computers throughout a computer network. ▪There is a danger of hacking, particularly with wide area networks. Security procedures are needed to prevent such abuse, e.g. a firewall. But we could find some solutions to them like: Looking for some cheaper cabling and file servers or maybe discussing some percentage decrease from the normal price as we need to buy equipment for two different networks (one in each building) Managing the large networks in the school is not a problem for us as we have a professional in these types of technical things that has already been employed and that is in charge of all the school’s technical problems. If the file server breaks down we will also have the network in the opposite school to be used until the data we need is accessible again and otherwise data will not be lost as we will have it all saved in the hard drive of another computer outside of the network. We will always be sure that we have antivirus software installed in every computer so that we will not allow the virus to spread. Accordingly, we will keep the same method for all the student of accessing its account with an ID in this case the number of the student and password which is a secret word or phrase that the student uses to gain admittance or access to the account. This method provides confidentiality for each students and its personal account, Avoiding any hackers. As a matter of course we also need to supply you some information about the two main types of networks LAN and WAN. LAN stand for local area network which covers a small area such as one site or building meaning it would be the types of network we would use for our school, they are often connected to WANs, for example our school network could be connected to the Internet. In the other hand WAN stands for wide area network which covers a large geographical area. Most WANs are made from several LANs connected together. They can be connected together using the Internet, leased lines or satellite links.

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