GCSE Edexcel Computer Science

All the content you need to know for GCSE Computer Science

What is the distinction between a logical shift and an arithmetic shift?

A logical shift involves moving each bit in a bit pattern a certain number of places to the left or right, and the empty spaces left are filled with zeros.

An arithmetic shift performs a similar operation, but on a shift right, the most significant bit (MSB) is copied into the empty spaces on the left, preserving the sign of the number in two's complement representation, whereas on a logical shift left, zeros are added to the right.

Could you define what an array is in computer science?

An array is a data structure that can store multiple data items of the same data type under a single identifier. Arrays increase the efficiency of programs because if they were not used, a separate variable would have to be used for each element, for example, name1, name2, name3.

Can you explain the stored program concept?

The stored program concept is the idea that program instructions as well as the data being processed are stored in the computer's memory. This allows the computer to perform a variety of tasks by loading different programs into memory and executing their instructions. Previously, computers were built to perform just one job and had to be rewired to perform another.

What are the main components of the central processing unit (CPU) and what are their primary functions?

The CPU consists of three main parts that work together to process data

Please describe the fetch-decode-execute cycle performed by the CPU.

Fetch: The Control unit checks the PC for the address of the next instruction and loads it onto the MAR. The address from the MAR is used as the address to retrieve the instruction from. The instruction arrived at the MDR, then it is copied from the MDR onto the CIR. The PC is then incremented.

The Control Unit (CU) decodes the instruction stored in the Current Instruction Register (CIR) and splits it into two main components Opcode and Operands.

Execute: The instruction is executed and the results goes into the ACC, then it will be sent back to RAM, to be stored.

Why is secondary storage necessary in a computer system?

Secondary storage is needed because the computer's main memory (primary storage) is volatile, meaning it loses its data when the power is switched off. Secondary storage provides long-term, non-volatile storage for programs and data, allowing them to be saved and accessed even when the computer is turned off. When an application is opened, it is loaded from secondary storage into main memory.

What are the key differences between primary storage and secondary storage?

Primary storage (main memory) is volatile, has limited storage capacity (typically measured in GBs), and is directly accessed by the CPU with fast data access speeds. Examples of primary storage include RAM. Secondary storage is non-volatile, has a large storage capacity (ranging from GBs to TBs), and requires data to be transferred to primary storage before the CPU can access it, resulting in slower data access speeds compared to primary storage. Examples of secondary storage include hard disk drives (HDDs), solid-state drives (SSDs), CDs, DVDs, and USB sticks. Primary storage is essential for currently running programs and data, while secondary storage is used for the long-term retention of all data.

Could you outline the three types of buses found in a computer system and describe their roles?

The address bus carries the memory addresses of data or instructions between the CPU and memory.

The data bus transmits the actual data and instructions between the CPU, memory, and other peripherals.

The control bus sends control signals from the control unit to other components of the computer, coordinating their actions.

What is the function of the CPU clock in a computer?

The CPU clock is a tiny quartz crystal that vibrates at a constant rate, producing a series of regular electrical pulses. Each pulse is referred to as a clock cycle, and the clock speed (measured in Hertz) indicates the number of cycles per second. The CPU clock synchronises the operations of all parts of the CPU, ensuring that instructions are executed in the correct order and at a consistent pace.

How does magnetic storage operate and what are some examples?

Magnetic storage devices include hard disk drives (HDDs) and magnetic tape drives.

A HDD contains a stack of circular, metal platters that spin at high speed. These platters are coated with a magnetic material. Each platter has an electromagnetic read-write head on an arm that moves across the surface.

Data is stored on these platters as magnetic patterns. Each tiny area on the platter can be magnetised to represent a binary number: a north-to-south (1) or south-to-north (0).

To read data, the read head passes over the spinning platter and detects the magnetic orientation of these tiny areas. To write data, the write head magnetises these areas with the appropriate north or south pole.

What is the principle behind optical storage and what are common examples?

Optical storage devices, including CDs, DVDs, and Blu-ray discs, use patterns of pits and lands on their surface to represent data.

Writing: A laser beam is fired to burn the disk to create pits (0) and land (1)

Reading: A laser beam is shone onto the disc, and the reflected light is interpreted as 1s and 0s based on whether it hits a pit or a land.

How do SSD write?

& read?

What are some typical forms?

Write: an electrical current is applied to the transistor, this forces electrons, through the barrier to trap them in electron pools. A full pool is 0 and an empty pool is 1.

Read: a small voltage is applied. If the pool is empty, the transistor turns on, a 1 is read. If the pool is full, the transistor does not turn on, a 0 is read.

Uses: USB sticks, phones, smart watches etc.

What is a key advantage of magnetic storage technologies?

A significant advantage of magnetic storage is its high capacity for storing data.

What is a notable disadvantage associated with magnetic storage devices?

A notable disadvantage of magnetic storage devices is that they have moving parts, which makes them more susceptible to physical damage and can lead to a shorter lifespan compared to solid-state storage.

What is a primary benefit of using optical storage media?

A primary benefit of optical storage is that the media, such as CDs and DVDs, are portable and relatively cheap.

What is a significant limitation of optical storage technologies?

A significant limitation of optical storage is that they tend to have a slower access speed compared to magnetic and solid-state storage. They are also prone to scratches.

What is a major advantage of solid-state storage solutions?

A major advantage of solid-state storage is its very fast data access speed due to the absence of moving parts. They are also more durable and reliable.

What is a key drawback of solid-state storage in some applications?

A key drawback of solid-state storage can be the relatively limited number of read-write cycles it can endure over its lifespan.

They also tend to be more expensive per unit of storage compared to magnetic storage.

Could you define what an embedded system is?

An embedded system is a small computer system designed to perform a dedicated task within a larger electronic or mechanical system. It typically works in real-time and must respond immediately to an event or request.

What are some characteristic features of an embedded system?

• Embedded systems are often single-purpose

• have customised hardware and software

• have limited memory and processing power

• are designed for low power consumption

• may have wireless connectivity

• often have a minimal or no user interface

• are typically small in physical size

• are responsive to their environment

• require low maintenance

• usually operate in real-time.

What are the typical hardware components found in an embedded system?

The hardware of an embedded system typically includes a long-life power system (like a battery), a microcontroller (which contains the CPU, memory, and input/output peripherals), sensors and other input devices to gather information, and actuators or other output devices to produce a response. It also includes memory (RAM and Flash).

Could you provide some examples of common embedded systems?

Examples of embedded systems include a washing machine that regulates water usage, a drinks dispenser that manages drink orders, an insulin pump that monitors blood glucose levels, an anti-lock braking system (ABS) in a vehicle, and a burglar alarm system. The navigation system in a car is also an example.

What is an Operating System?

It manages computer hardware and software.

Provides an interface between the user and hardware.

Provides common services for programs e.g. malware removal

What are the 5 main tasks performed by an Operating System?

• Process management

• Memory management

• File management

• User management

• Peripheral management

What does the process management task of an Operating System involve?

Process management in an operating system involves overseeing the execution of programs by the CPU. When a program is opened, it is copied into secondary storage, then moved into main memory so that the CPU can execute it. The OS allocates CPU time to different processes, enabling multitasking where several processes appear to run concurrently. Scheduling algorithms, like round-robin, ensure that each process gets a fair share of CPU time.

Could you explain the memory management role of an Operating System?

Memory management is the operating system's task of controlling and coordinating the computer's main memory (RAM).

When a process is loaded into memory, the OS allocates blocks of memory called pages.

It keeps track of which parts of memory are currently being used and by which processes.

If memory becomes full, the OS may temporarily move inactive processes out of main memory into an area on the hard drive called virtual memory, freeing up RAM for active processes.

What is the function of file management within an Operating System?

File management is the responsibility of the operating system to organise and keep track of files and folders stored on the computer's storage devices, such as hard drives and SSDs.

The OS maintains a hierarchical structure of directories (folders) and files.

It handles operations such as creating, deleting, copying, moving, and renaming files and directories.

File permissions control who can do what with each file, ensuring data security.

What does User Management entail within an Operating System?

User management involves the operating system managing user accounts and their access rights. The OS requires users to log in with usernames and passwords to authenticate themselves. It controls access to shared computer resources and ensures that users only have access to the files and applications they are authorised to use.

What is Peripheral Management as performed by an Operating System?

Peripheral management involves the operating system communicating with and controlling the computer's peripheral devices, such as printers, keyboards, and mice.

The OS uses special software called device drivers to enable communication between the operating system and each specific peripheral device.

These drivers need to be kept up to date so that peripherals continue to work as expected.

What is the Round Robin algorithm in the context of Process Management?

The round-robin algorithm is a scheduling algorithm used by the operating system in process management of CPU time.

In this algorithm, each process in the ready queue is allocated a short period of CPU time, known as a time slice or quantum.

If a process does not complete its execution within its time slice, it is moved to the back of the ready queue, and the next process in the queue gets its turn.

This ensures that all processes get some CPU time and prevents any single process from monopolising the CPU.

What is utility software?

Utility software comprises programs designed to maintain, analyse, configure, and optimise the computer system. These programs typically focus on tasks such as file management, system diagnostics, security, and performance enhancement.

What is Disk Defragmentation software and what does it do?

Disk defragmentation software is a utility program used to speed up access to files on a hard disk drive (HDD). It works by rearranging fragmented files so that all their parts are stored contiguously on the disk. This reduces the time it takes for the hard drive's read/write head to access all the pieces of a file.

What is file repair software used for?

File repair software is a type of utility software used to attempt to recover data from damaged or corrupted files. It works by scanning the damaged file for recoverable data structures and trying to reconstruct the file's contents.

What is backup software and what is its purpose?

Backup software is a utility program designed to create copies of important files, folders, or entire drives. Its purpose is to protect data from loss due to hardware failure, software corruption, accidental deletion, or other disasters, allowing for the restoration of data if needed.

Why does fragmentation occur on a hard disk drive?

1. Files are handled normally over time (deletion, saving modification etc.)

2. At first the files are stored contiguously but as files are deleted, new smaller gaps of free space are created.

3. Then new files have to be stored in these gaps, but many do not fit so are split between these gaps making them non-contiguous.

4. So then files are broken up across the HDD, resulting in slower read & write speeds.

Do Solid State Drives (SSDs) typically experience data fragmentation in the same way as Hard Disk Drives?

Yes but it does not affect their speed as data retrieval time is the same as there are no moving parts.

What is antimalware software and how does it function?

Antimalware software is a type of utility software designed to protect the computer system from malicious software (malware) such as viruses, worms, spyware, and ransomware.

It works by scanning files and system memory for known malware signatures and suspicious behavior.

If malware is detected, the antimalware software can quarantine, remove, or block it.

More sophisticated antimalware uses heuristic analysis to look for suspicious code patterns even in previously unknown malware.

What characterises robust software?

They can handle unexpected inputs (out of their problem space) without crashing.

They are thus dependable and reliable in adverse conditions.

What are three practices that can contribute to making software more robust?

Three practices to make software more robust include adhering to good programming practices, carrying out regular code reviews, and keeping an audit trail. Good programming practices involve writing clear, well-structured code that anticipates potential errors.

Regular code reviews by other programmers can help identify and fix potential weaknesses.

An audit trail helps in tracing what changes were made to the code and when, which can be useful for debugging and identifying the cause of issues.

What are code reviews in software development?

Code reviews are a process where other programmers examine and check code that has been written. The purpose of code reviews is to identify potential bugs, errors, and areas for improvement in the code before it is deployed. This helps to ensure code quality, maintainability, and robustness.

What are audit trails in software development?

Audit trails are logs that record what changes were made to the software code and when, along with who made the changes.

Audit trails are useful for tracking the history of the software development, debugging issues, and ensuring accountability.

Could you provide examples of low-level programming languages?

• Machine code

• Assembly language

What are some key features of low-level programming languages?

Low-level languages are closely related to the computer's hardware. Machine code consists of binary instructions that the CPU can directly execute. Assembly language uses mnemonic codes that correspond to machine instructions. Low-level languages require a detailed understanding of the computer's architecture and are often machine-specific. They give the programmer direct control over hardware but are difficult and time-consuming to write.

What is assembly language?

Assembly language is a type of low-level programming language that uses symbolic representations, called mnemonics, for machine instructions.

Each mnemonic typically corresponds to a single machine code instruction.

Assembly language needs to be translated into machine code by an assembler before it can be executed by the computer.

What are some typical uses for low-level programming languages?

Low-level languages are often used for programming directly with computer hardware and for writing code that needs to be very efficient in terms of memory usage and execution speed. This includes writing device drivers and programming for embedded systems.

Could you give 3 examples of high-level programming languages?

• C++

• Java

• Python

What are some characteristic features of high-level programming languages?

+ Readable & easy to use as they use English-like keywords and syntaxes

+ Problem orientated: programmers get to focus on the logic of the problem rather than details of the underlying hardware.

+ They are machine independent and thus device portable

= A single line of high level code corresponds to many lines of machine code

- Usually less resource efficient than low level languages.

What are some common uses for high-level programming languages?

High-level languages are widely used for developing a wide range of applications, including desktop software, web applications, mobile apps, and artificial intelligence programs. They provide libraries and tools that simplify complex programming tasks.

What are three disadvantages of using low-level programming languages?

Time: Low-level languages are time-consuming to write.

Technicality: Low-level languages are hard to learn and use effectively.

Portability: Low-level languages are often not portable between two devices.

What is one advantage of using low-level programming languages?

One advantage of low-level languages is that they allow for very efficient code in terms of memory usage and execution speed, giving the programmer direct control over the hardware.

What are three advantages of using high-level programming languages?

Three advantages of high-level languages are that they are easier and faster to write due to their more human-readable syntax, they are more portable across different computer architectures, and they allow programmers to focus on the problem rather than hardware details.

What is one disadvantage of using high-level programming languages?

One disadvantage of high-level languages is that they may be less efficient in terms of memory usage and execution speed compared to carefully written low-level code, as the translator may not always produce the most optimised machine code.

What is a compiler?

A compiler is a program that translates the entire source code of a high-level language program into machine code before the program is executed. The translated machine code is then saved as an executable file that can be run independently.

What are three advantages of using a compiler?

Three advantages of using a compiler are that the program is translated only once, resulting in faster execution of the compiled code. It can also optimise the code during compilation to improve performance, and the resulting executable file can be run without needing the compiler present.

What are two disadvantages of using a compiler?

- Entire Program needs to be compiled before running after any source code modification, this can take time

- If there are errors the programmer, they are reported after the program finished running which wastes time and is harder to decode.

What is an interpreter?

An interpreter is a program that translates and executes the source code of a high-level language program line by line. It does not create a separate executable file.

What are two advantages of using an interpreter?

Three advantages of using an interpreter are that it provides immediate feedback as code is executed line by line, making it easier to debug.

It is also platform-independent, as long as an interpreter is available for that platform, the code can be run. Interpreters are often better for testing and prototyping due to the ability to run code incrementally.

What is one disadvantage of using an interpreter?

They are generally slower than compilers because every run the code needs to be translated.

What are assemblers?

Assemblers are programs that translate assembly language code into machine code. They perform a one-to-one translation of the assembly language mnemonics into the corresponding binary instructions that the CPU can understand and execute.

Explain five motivations for establishing connections between computers on a network

There are several reasons to connect computers on a network,

including the ability to share data and software,

the capacity to share printers, hard drives and other hardware peripherals,

the facility to enable rapid deployment of new software and updates,

the potential to enable people to communicate with each other using services such as the web and web-based software,

and the possibility of collaborative working and video conferencing.

What constitutes a Local Area Network (LAN)

A local area network is a network arrangement involving two or more computing devices connected together within a relatively small geographical area, allowing users to differentiate various networks based on the physical area they encompass.

In what environments are Local Area Networks typically situated

A local area network is commonly found within a confined geographical space, such as a classroom, a school, an office, or a home, often being managed by a local team or individual with control over the network.

Describe the characteristics of a Local Area Network

A local area network spans a small geographical area.

It is typically used in small organisations

LANs are often connected to WANs, e.g. the internet.

What is meant by a Wide Area Network (WAN)

A wide area network is formed by connecting separate LANs across a larger geographical area, allowing large companies to establish networks connecting their different sites and enabling computers in diverse locations to communicate and share resources.

Provide an example of a Wide Area Network

The internet serves as a prominent example of a wide area network, connecting billions of digital devices worldwide.

What is an IP address

An IP address is a distinct numerical label assigned to each device connected to a computer network that utilises the Internet Protocol for communication, enabling data to be sent and received correctly.

An IP address is a unique numeric identifier for a device when it is connected to a network. This allows data to be sent and received correctly at the right device.

Contrast IPv4 and IPv6, highlighting their key distinctions

There are currently two versions of IP addresses in use

What is a dynamic IP address

A dynamic IP address is an IP address that is not permanently assigned to a device. Internet-connected devices are often allocated an IP address from a pool of available addresses each time they connect to the internet, and this address may change upon the next connection.

Define a domain name

A domain name is a human-friendly textual address used to identify a website or other internet resource, making it easier for users to remember and access online locations instead of using numerical IP addresses.

Explain what a URL is and what the acronym stands for

A URL stands for Uniform Resource Locator and is a complete web address used to locate a specific page or other resource on the internet. It acts as the address for a resource on the World Wide Web.

Describe the sequence of events when a HTML web page is requested

When a user enters a URL into their web browser, the browser sends a request containing the URL to a DNS server.

The DNS server then translates the domain name part of the URL into its corresponding IP address.

Once the browser has the IP address of the web server hosting the requested page, it sends an HTTP request to that server.

The web server then finds the requested page and sends it back to the browser in the form of data packets, which the browser then interprets and displays as the web page.

What journey do packets do across the network (including verification)?

1. The sending computer breaks down the data of a message or file into smaller units called packets.

2. These packets are then directed through the network by routers, which inspect the destination address in each packet and determine the most efficient path to the receiving computer.

3. The packets may take different routes across the network and might arrive at the receiving computer out of order.

4. The receiving computer reassembles these packets into the original message or file once all packets have been received

5. It then verifies the packets integrity using checksums within the packet headers.

What are Routers?

Routers are hardware devices that form a crucial connection point between two or more networks, facilitating the forwarding of data packets between them.

What does a router do when it receives a packet?

1. It examines the destination IP address located in the packet's header.

2. Using this address and its internal routing table, the router then determines the optimal next hop or the next network segment towards the packet's final destination.

3. It removes the MAC addresses previously on the packet and adds the MAC address of itself and the next node the packet is being forwarded to

4. It proceeds to forwards the packet accordingly.

Identify the three main components of a data packet and describe the information contained within each?

A data packet typically comprises three parts:

Header:

• IP of destination and sender

• Sequence number

• Checksum

• Total sum of packets

Body:

• Data being sent

Footer:

• End of packet flag

Describe the four steps a computer undertakes upon receiving data packets

When a computer receives data packets, it first checks that all the packets have been received.

Secondly, it verifies that each of the received packets is complete and uncorrupted by using the checksum information in the header.

Thirdly, it uses the sequence numbers in the headers to reassemble the packets into the correct order, reconstructing the original data.

Finally, once the data is reassembled and verified, the computer can then process or display the information contained within the packets, such as rendering a web page in a browser.

What are the distinctions between fibre-optic and copper cables, and in what scenarios is each type typically used?

Fibre-optic cable transmits data as pulses of light through thin strands of glass, offering high bandwidth, long range (up to 100 km), and immunity to electrical interference, making it suitable for long-distance communication and high-speed data transfer. Copper cable transmits data as electrical pulses and is a more common and affordable material for shorter distances (up to 100 m for copper wire and up to 80 km for fibre-optic cable) and local area networks. Copper wire is susceptible to electrical interference.

When is fibre-optic cable typically preferred over copper cable?

Fibre-optic cable is typically preferred when high bandwidth, long transmission distances, and immunity to electrical interference are required, such as in wide area networks and scenarios with potential electromagnetic interference.

When is copper cable typically preferred over fibre-optic cable?

Copper cable is typically preferred for shorter distances and local area networks due to its lower cost and ease of installation.

What is bandwidth in the context of network communication?

Bandwidth is the total volume of data that can be transferred by the network at one time, this total bandwidth is shared between all connected devices

What are the key characteristics and common applications of Wi-Fi technology?

Wi-Fi is a wireless communication medium that uses radio waves to transmit data over short to medium ranges (up to 100 m)

it is commonly used to connect devices to local area networks and the internet, offering flexibility and ease of installation.

It is susceptible to interference from walls and physical obstacles.

Easily wireless LANs can be created with Wi-Fi, allowing devices like laptops and consoles to connect without dedicated network cabling, provided they have the network ID and a password.

What are the defining features and typical uses of Bluetooth technology?

Bluetooth is a low-power, short-range (up to 10 m) wireless communication technology primarily used for pairing devices like peripherals (e.g., wireless headphones, keyboards) to computers or smartphones. It is designed for personal area networks.

What are the main attributes and typical applications of Zigbee technology?

Zigbee is a low-power, low data rate wireless technology with a range of up to 100 m, often used in home automation and the Internet of Things (IoT) for connecting smart devices like lighting and sensors.

What are the key features and common applications of Radio-Frequency Identification (RFID) technology?

RFID uses radio waves to automatically identify and track tags attached to objects over close proximity (around 10 cm) or medium range (up to 1 m), commonly used in contactless payment systems, access control, and inventory management.

What are the defining characteristics and typical uses of Near-Field Communication (NFC) technology?

NFC is a very low power, very close proximity (around 10 cm) wireless communication technology that enables short-range data exchange between devices, commonly used for contactless payments, data sharing, and device pairing. It requires the devices to be very close together to function.

What constitutes a mixed network environment?

A mixed network is a network that combines both wired (e.g., Ethernet) and wireless (e.g., Wi-Fi) connection methods to connect devices within a local area network. This allows devices to connect via cables or wirelessly, offering flexibility in network design.

What are the advantages associated with utilising wired networks?

Wired networks generally offer more secure connections,

higher and more reliable data transfer speeds with high bandwidth (up to 10 Gigabits per second),

lower susceptibility to interference compared to wireless networks. The cables in wired networks have protective coverings making them less susceptible to interference.

What are the disadvantages typically encountered with wired network setups?

Wired networks can be difficult and costly to install due to the need for physical cabling to each device, they offer limited flexibility as devices cannot easily be moved without recabling, and the physical cables can be disruptive and time-consuming to install.

What are the benefits of implementing wireless networks?

Wireless networks provide ease of installation and greater flexibility as devices can connect without physical cables and be easily moved within the network's range. It is easy to add new wireless access points to extend connectivity.

What are the drawbacks commonly associated with wireless networks?

Wireless networks can experience lower data transfer speeds (up to 3.2 Gigabits per second on newer networks), have a shorter effective range due to walls and obstacles, are more susceptible to interference, and can pose security concerns if not properly configured.

What are protocol layers in the context of network communication?

Protocol layers are a conceptual division of network communication into distinct levels, each with its own set of rules (protocols) that define how data is formatted, transmitted, and received. Each layer performs a specific function, simplifying the complexity of network communication. Network protocols work in layers; those in the top layer use the services of the layer below.

What are protocols in network communication?

Why are they needed?

Protocols are a set of rules and procedures that govern how devices on a network communicate with each other, ensuring that data is transmitted and received correctly.

Protocols are needed:

• to ensure that data is formatted correctly,

• to ensure that addressing is correct,

• to ensure that data is transmitted in an understandable way,

• to ensure that errors are detected.

What essential components must all network protocols include?

All network protocols need to include data formats, addressing schemes to identify senders and recipients, methods for transmitting data in a comprehensible way, and error detection mechanisms.

What is the File Transfer Protocol (FTP) and what is its primary purpose?

FTP is an Application Layer protocol used for transferring files between a client and a server over a network. Its use is to transfer files between computers.

What is the Hypertext Transfer Protocol (HTTP) and for what is it primarily used?

HTTP is an Application Layer protocol used for transferring data on the World Wide Web, forming the foundation of communication for web browsers and servers. Its use is for web browsers to access websites.

What is the Hypertext Transfer Protocol Secure (HTTPS) and what is its main function?

HTTPS is a secure version of HTTP that encrypts the communication between a web browser and a server, providing secure transactions and protecting sensitive data. Its use is for secure web browsing, e.g. when logging in to a website.

What is the Simple Mail Transfer Protocol (SMTP) and what is its role in email communication?

SMTP is an Application Layer protocol used for sending email messages from a client to a mail server or between mail servers. Its use is to send email.

What is the Post Office Protocol (POP) and how is it used in email retrieval?

POP is an Application Layer protocol used by email clients to retrieve email messages from a mail server. Its use is to retrieve email from a server and then the email is deleted off the server.

What is the Internet Message Access Protocol (IMAP) and how does it facilitate email management?

IMAP is an Application Layer protocol used by email clients to access and manage email messages on a mail server, allowing users to organise their emails into folders and synchronise across multiple devices. Its use is to access and organise email on a server.

In what order does data traverse the layers of the TCP/IP stack during transmission?

During data transmission, data originates at the Application Layer, then passes down through the Transport Layer, where it is segmented, followed by the Internet Layer, where IP addressing and routing are handled, and finally to the Link Layer for physical transmission over the network.