Computer Networks, Connections and protocols

• A LAN is a local area network that covers a small geographical area on a single site.

  A WAN is a wide area network that is used by large networks over different locations to connect other small networks together.
• How can bandwidth affect network performance?

  Bandwidth is how much data that can be transmitted across a network over a period of time. The greater bandwidth, the more data that can be transmitted across a network.
• How can wired/wireless connections affect the performance of a network?

  Wired connections are faster and more reliable than wireless. Wireless depends on signal quality and is more susceptible to obstructions like intereference from other networks or walls.
• How can number of users affect network performance?

  A larger number of users can cause network congestion, meaning that data packets are queued before they are transmitted. Some users may be downloading/using larger data which requires more bandwidth so other users will have to share a smaller amount.
• What is a client-server network? Explain pros/cons.

  A client-sever network is managed by a server. Clients send requests for data to the server and the server processes the request and responds.

  Pros: Easier to keep track of files as they are managed in the same place, easier to perform backups/install/update software. Easier to manage network security.

  Cons: Expensive to set up, can become overloaded, if server goes down, clients lose all data.
• What is a peer-to-peer network? Explain pros and cons.

  All computers are connected equally without a central server. Files are stored on individual devices and can be shared with others.

  Pros: Easy to maintain, cheaper as no expensive hardware, no dependence on server.

  Cons: Devices need updates/security installed individually. Backups are more difficult. More likely to be slower. Easier to lose track of what is stored where.
• What are the types of hardware needed for networks?

  Transmission media: cables/radio waves

  WAP: A switch that allows devices/Wi-Fi networks to connect wirelessly to a network.

  NIC: Connect devices to a network/transmits data.

  Routers: Direct data to their destination, connect LANs to the Internet.

  Switches: Allows devices to connect together to form a network. Receive data from a device and transmit data to device with correct MAC address.
• What do switches do?

  Allows devices to connect together to form a network. Receive data from a device and transmit data to device with correct MAC address.
• What do routers do?

  Transmit data across networks by using data packets.

  Connect LANs to the internet.
• What do WAPs do?

  Allows devices to connect to a network and provides Wi-Fi to a network.
• How does the DNS work?

  1. A user types a URL into a website and a request is sent to the DNS to find the matching address.
  2. The DNS will make request to different DNS servers until it finds an address that matches.
  3. The process continues until the DNS matches the IP address.
  4. The DNS then sends the IP to the user.
  5. If the IP address is not found, an error message is returned.
• Hosting is the process of providing a service to a client, such as a website or email.
• Compare IP and MAC addresses.

  IP: Used when sending data between TCP/IP networks. IP addresses are written as denary numbers.

  MAC: Assigned to devices by the manufacturer. Cannot be changed. Are hexadecimal numbers.
• What are the advantages of having layers?

  Layers are self-contained, one can be changed without it affecting the others.

  Breaks communication into manageable pieces.
• What is the HTTP protocol?

  Hyper Text Transfer Protocol. Used by web browsers to access websites/communication.
• What is the HTTPs?

  HTTP but with encryption. Encrypts all information.
• What is FTP?

  Used to access, edit and move files between devices on a network.
• What is POP3?

  Used to retrieve emails. Once email is downloaded, it is deleted from server.
• What is IMAP?

  Internet Message Access Protocol. Used to retrieve emails from a server. Server holds email until it is deleted, user only receives a copy.
• What is SMTP?

  Used to send emails/transfer emails between servers.
• What are network protocols?

  A set of rules for hardware and software to enable devices across networks to communicate with eachother.
• What are the different layers?

  4. Allows communication between servers and networks. Turns data into websites. (HTTTP, FTP, SMTP)

  3. Splits data into packets- checks data is sent/delivered (TCP)

  2. Adds the IP address of sender/recipient. Makes connections between networks and directing data. (IP)

  1. Converts data into electrical signals over network. Adds MAC address of sender/recipient. (Ethernet)
• What are advantages of connecting computers together to form networks?

  Computers can share the same internet connection and the same printer/scanner. It is easier to share files.
• Which pieces of hardware are needed to create a WIRED local network.

  NIC- allows devices to connect to network

  Ethernet- cable to connect devices together
• The computers will all be connected, and will store their own files. Identify the name for a network organised in this manner.

  Peer to peer network
• What are advantages of using a peer-to-peer network?

  Cheaper to set up as no expensive hardware required. If one device fails the rest of the network is still working.
• What does a WAP do?

  Allows wireless devices to connect to a network.
• Why do devices need IP addresses to connect to the internet?

  The IP address uniquely identifies the location of the device on the internet, allowing data to be sent between it and other devices.
• Why are MAC addresses needed in a LAN?

  MAC addresses uniquely identify each device connected to a network. This allows data to be directed to the correct device.
• Why is IMAP good for emails?

  Emails are kept on the server even after they have been read.

  Emails can be flagged as important or organised into folders.

  Inbox is updated each time it is connected.
• What are benefits of using layers?

  Breaks down processes into smaller, more manageable parts.

  Each layer can be changed without changing other layers.

  Developers only need to understand how one layer works to develop new products.
• How does the number of devices using a network affect the performance?

  Bandwidth is split across each device, there is less bandwidth for each device. Less data can be transmitted at the same time. Network congestion as devices have to wait longer before they can transmit data.
• What other factors can affect network performance?

  Bandwidth

  Wired or wireless
• What are tasks carried out by a router?

  Receives/forward packets to transmit data

  Converts packets between protocols

  Identifies the most efficient path to correct destination
• Why can number of devices on a network reduce network speed?

  Less data is transmitted at the same time so the time taken to receive data increases, can cause more traffic and collisions.

  More users means more data has to be transmitted

  Bandwidth has to be split between all devices using data, there is less bandwidth for each device

  More data packets to be sent, more data has to be retransmitted
• A standard is used in many devices and is made to allow compatibility with other devices. A standard has inbuilt security and is low cost for installation.
• A router receives packets as well as forward and transmit packets and identifies the most efficient path to a destination. A router also connects networks together
• What network is used to send emails?

  SMTP
• Why do protocols have layers?

  • Layers are self-contained so editing one layer will not affect any other layers
  • Helps group together specific protocols
  • A developer can focus on one layer specifically and use them to group together similar protocols
• Ethernet is the protocol used to connect devices in a wired LAN.