Stretch tasks Wired and Wireless Networks, Protocols and Layers

Round 1: Quiz Blitz

1. SMTP SMTP sends. POP and IMAP retrieve.
2. IMAP IMAP keeps mail on the server. POP normally downloads it and deletes it from the server.
3. Splits data into packets and checks they all arrive TCP handles reliability. IP handles addressing and routing.
4. True An IP address is assigned by the network and can change.
5. 32 IPv4 is 32 bits, IPv6 is 128 bits, and a MAC address is 48 bits.
6. Faster and more consistent; More secure Wired gives speed, reliability and security. Wireless gives convenience and mobility.
7. Application → Transport → Internet → Link Application, transport, internet, link.
8. https HTTPS encrypts the data, so intercepted traffic cannot be read.
9. Internet The internet layer adds addresses and routes packets across networks.
10. False Layering is about manageability and interoperability, not speed.
11. A set of rules for how data is transmitted Without shared protocols, two computers would be talking different languages.
12. FTP FTP is the File Transfer Protocol.

Round 2: Quick Fire

1. • An IP address is assigned by the network, can change, and routes data between networks
   • A MAC address is fixed by the manufacturer and identifies the hardware, within a local network
   Model answer

   An IP address identifies a device on a network: it is assigned by the network, can change, and is used for routing between networks. A MAC address identifies a piece of hardware: it is set by the manufacturer, never changes, and is used to deliver data within a local network.

2. • POP downloads email and normally deletes it from the server
   • IMAP keeps email on the server, so it syncs across devices
   Model answer

   POP downloads email and normally deletes it from the server, so it ends up on one device. IMAP keeps the email on the server, so it stays synced across every device.

3. • It breaks a complex problem into manageable parts
   • Each layer can be changed without affecting the others
   • Equipment from different manufacturers can work together
   • Faults are easier to find
   Model answer

   Layers break a complex problem into manageable parts, and each layer can be changed or replaced without affecting the others.

4. • HTTPS encrypts the data sent
   • So card details cannot be read if they are intercepted
   Model answer

   HTTPS encrypts the data travelling between the browser and the server, so customers' card details cannot be read even if the data is intercepted.

Round 3: Big Think

1. • TCP splits the data into packets
   • TCP numbers the packets, checks they all arrive and requests any missing
   • IP adds addresses and routes each packet across the networks
   • TCP reassembles the packets in the right order
   Model answer

   TCP splits the web page into packets and numbers them. IP adds the destination address to each packet and routes it across the networks, possibly by different paths. At the other end TCP checks that every packet has arrived, requests any that are missing, and reassembles them in the right order.

2. • Customers can connect their own devices and move freely
   • No cabling, so it is cheaper and quicker to install
   • Many devices can connect easily
   • Slower and less reliable: the signal weakens with distance and walls
   • Less secure, because the signal can be intercepted
   • So encryption and a password are needed
   • Bandwidth is shared between many customers
   • A justified conclusion
   Model answer

   Wireless lets customers connect their own phones and laptops and move freely around the cafe, and many devices can connect easily. There is no cabling to install, so it is cheaper and quicker to set up. However, wireless is slower and less reliable than wired: the signal weakens with distance and is blocked by walls. It is also less secure, because the signal travels through the air and can be intercepted, so the cafe should use encryption and a password. With many customers the bandwidth is shared, so it can slow down. Overall, wireless is the better choice for a cafe, because customers bring their own devices and a cable to every seat is impractical.

This or That

1. IMAP IMAP keeps mail on the server, so every device stays in sync.
2. IP address IP gets data to the right network. The MAC address then finds the right device on it.
3. A MAC address A MAC address is six pairs of hex digits. IPv4 is four denary numbers, like 192.168.1.24.
4. No: it makes intercepted data unreadable Encryption does not stop interception. It makes what is intercepted useless.
5. Link The link layer handles physical transmission over the cable or radio.
6. IPv4 addresses ran out 32 bits do not give enough addresses for every device. IPv6 uses 128 bits.
7. Bluetooth Bluetooth is short range wireless for connecting a few devices directly.
8. Only the link layer That is the point of layers: one can change without affecting the others.

Memory Match

• A 4 TCP: Packets, checking and reassembly
• B 3 IP: Addressing and routing packets
• C 5 HTTP: Requests and sends web pages
• D 1 FTP: Transfers files to and from a server
• E 6 SMTP: Sends email
• F 2 IMAP: Keeps email synced on the server

Sort It

1. Transport Splits data into packets and makes sure they all arrive That is the job of the transport layer.
2. Application Provides services to the user's software, such as a browser That is the job of the application layer.
3. Transport TCP TCP splits data into packets and makes delivery reliable.
4. Link Wi-Fi Wi-Fi handles transmission over radio waves.
5. Application HTTP HTTP provides a service to the user's software: the web browser.
6. Link Ethernet Ethernet handles transmission over the cable.
7. Internet Adds addresses and routes packets across networks That is the job of the internet layer.
8. Internet IP IP addresses and routes packets.
9. Application SMTP Email protocols work at the application layer.
10. Link Handles the physical transmission over the medium That is the job of the link layer.
11. Transport UDP UDP is the transport layer's other protocol.
12. Application FTP File transfer is a service for the user's software.