1.3 past paper questions

Explain what a protocol is and why they are important in network communications.

• A set of rules for communication/ transmission/transfer of data between devices

• Allows standardisation as different devices have different OS/hardware

• Protocols allow for data to be exchanged in a predictable way/ in the correct format

Describe three different pieces of networking hardware in a client-server network apart from the clients and servers themselves.

Router

• Connect networks together

• assign IP addresses to devices

• Examines data and packets and forwards them

Gateway

• connects different types of networks

• translates protocols from one network to another

NIC

• gives each device a MAC address/unique ID 

• allows a computer sysrem to connect to the internet

Give three advantages to the business of connecting computers together in a LAN.

• Share hardware (e.g. printers)

• Share files

• Share Internet connection

• Centralised security

• Log on / access files from any machine on the LAN

Explain why protocol layering is used.

• To apply protocols in order / one after the other

• To provide independence of layers / Layers can be modified without affecting other layers / Layers are selfcontained

• Hides details from previous or next layer(s) / is an abstraction

• Each layer is well defined / does a specific job

• Breaks tasks down into manageable units

• Hardware/software can be manufactured to fit into one specific layer

• Allows for standards for individual tasks/layers to be developed / for compatibility

Explain what happens at the application layer of the TCP/IP stack when using this program.

•  Protocol to be used is decided based on the application

•  E.g. HTTPS for browser based service / SMTP/IMAP for messaging service

• Adds encryption

• Passes on to transport layer to send

• Gets data from transport layer when receiving

• Unpacks message ready for display / removes headers or other non-viewable data

• Decrypts message

Explain what happens at the link layer (sometimes referred to as the “network interface layer”, “network access layer” or simply the “network layer”) of the TCP/IP stack when using this program.

• Receives (layered) data from internet layer to send

• MAC addresses are added to the packet

• Passes and receives data across wireless network (to WAN / other machine)

• Passes (layered) data back up to internet layer when receiving

Explain one advantage of using layers in the protocol TCP/IP.

• Allows different layers to be worked on independently

• Allows layers to be replaced/upgraded without affecting others

• Allows for layers from different providers to be used interchangeably

Describe what is meant by the term ‘client-server’ in this context

• Client computers connect to server

• Server provides access to a resource/service

• In this case hotel staff use client computers to connect to database on server (or other sensible example).

Explain the purpose of a network switch.

• Joins computers/devices together on a LAN

• Receives packets/data

• Recipient’s address is given in packet header/it uses the mac address

• Send packets/data

• Out the correct port /to the specific computer device