3.3 Networks (OCR A Level Computer Science) Flashcards

The TCP/IP model consists of four layers: Application, Transport, Internet and Link.

Packet switching is a method of data transmission where data is broken into packets, each of which can take its own route to the destination and be reassembled at the end.

The application layer interacts directly with software applications and prepares data for transmission by converting it into a suitable format for the network.

True.

The layered design allows for changes to be made to one layer without affecting the others, which enables easier updates and improvements.

At the Internet layer, each packet is given a header containing the sender's and receiver's IP addresses.

An IP address is a unique identifier for a device on a network, used to deliver data to the correct destination.

The Domain Name System (DNS) is a distributed system that translates human-readable domain names into IP addresses so computers can locate and connect to websites.

The main benefit of using the Domain Name System (DNS) is that it allows us to use easily remembered domain names instead of having to remember difficult IP addresses.

When you type a URL into your browser, the DNS translates the domain name into its associated IP address so your computer can connect to the website's server.

The DNS resolver is the first stop in the DNS lookup process; it checks its cache for the IP address and, if not found, queries the DNS root servers to find the domain's IP address.

An Authoritative DNS server is a server that holds the actual DNS records for a domain and provides the final answer to DNS queries about that domain.

The DNS root server directs the resolver to a TLD server, which stores the domain's information.

True.

DNS allows users to use easily remembered domain names instead of having to remember complex IP addresses for every website.

After receiving the IP address from DNS, the browser sends an HTTP or HTTPS request to the server at that IP address to retrieve and display the web page.

A local area network (LAN) is a network contained within a small geographical location, usually with all hardware owned by a single entity.

A wide area network (WAN) is a network that connects multiple LANs over a large geographical area, typically using third-party connections.

Two advantages of using a LAN are centralised management of updates and backups, and the ability to share files and resources among users.

One disadvantage of a LAN is that networks are more prone to attacks than standalone computers.

A wide area network (WAN) allows users in different locations to share data and resources as if they were on the same network.

A LAN is typically owned by a single entity, while a WAN uses third-party connections.

False.

A LAN is generally more secure than a WAN because all its hardware is owned and managed by a single entity, whereas a WAN uses third-party connections, making it more vulnerable.

The Internet is a real-world example of a wide area network (WAN).

Packetising is the process of dividing a large message into smaller, manageable units called packets.

A packet header usually contains the source and destination IP addresses, sequence number, protocol, packet length, and checksum.

In packet switching, data is broken into smaller units called packets before transmission.

False.

Packets can take different routes through the network and are reassembled at the destination.

Circuit switching is a communication method where a dedicated communication path is established between two devices for the duration of their conversation.

Packet switching allows for efficient use of network resources as packets can be routed independently using available bandwidth.

In circuit switching, all data follows the same path between two devices.

Packet switching can cause packets to arrive out of order or be delayed, making it less suitable for real-time services that need a steady data stream.

Hacking is the act of gaining unauthorised access to a system or network to steal or manipulate data, disrupt services, or cause damage.

A virus is a malicious software program designed to spread from one computer to another and interfere with normal operations.

A virus attaches itself to legitimate programs or files and spreads when they are transferred, while a worm is a standalone program that replicates itself automatically over networks without needing to attach to a program.

Ransomware is malware that encrypts a user’s files and demands a ransom payment to decrypt them, causing data loss and financial damage.

A Denial of Service (DoS) attack is when a computer floods a server with so many requests at once that the server can’t respond, making it crash or become unavailable to users.

In a SQL injection attack, malicious SQL statements are inserted into an entry field to exploit a website’s security vulnerabilities.

The main aim of phishing is to steal sensitive information by tricking users into providing details on a fake website.

A firewall is a network security system that monitors and controls network traffic based on predetermined security rules.

A modem is a device that modulates and demodulates analogue signals to enable computers to transmit data over telephone or cable lines.

A router routes data between networks by analyzing data packets and determining the best path to reach their destination.

A data packet contains a header with information about the packet and a payload which is the actual data being sent.

A Network Interface Card (NIC) is a hardware component that enables a device to connect to a network and send or receive data packets. Each NIC has a unique MAC address.

A wireless access point (WAP) acts as a central transmitter and receiver of Wi-Fi signals, allowing devices to connect wirelessly to a wired network.

A hub is a networking device that connects multiple devices and passes all data to every connection, while a switch only sends data to the device it is intended for.

False.

A switch only sends data packets to the intended device, not to all devices.

An Ethernet cable is a common type of network cable used for wired networks, capable of transferring data at various speeds, such as 10 Mbps, 100 Mbps, 1 Gbps, and 10 Gbps.

A client-server network is a network where powerful and reliable server computers control the network and provide services such as files, email, or web access to clients.

Two key benefits of a client-server network are easier central management and higher reliability as resources are managed centrally.

In a client-server network, if the server goes down, services could become unavailable.

False.

Client-server networks are typically used in larger organisations where centralised control, reliability, and security are important.

A peer-to-peer network is a network where all computers share equal responsibility, have equal status, and there is no central server.

A key benefit of a peer-to-peer network is that it is easy to set up and less expensive than a client-server network, as no central server or administrative staff are needed.

True.

In a peer-to-peer network, each user is responsible for their own machine’s security, backup, and data management.

Peer-to-peer networks are often used in home networks and small businesses.