Wired and wireless networks, protocols and layers
Wired vs wireless, IP and MAC addressing, common protocols and the idea of layers.
Learning Objectives
- 1Compare the benefits and drawbacks of wired versus wireless connections
- 2Explain the principle of encryption
- 3Describe the format and purpose of IP addresses and MAC addresses
- 4Explain the principle and purpose of a standard
- 5State the purpose of common network protocols
- 6Explain the concept and benefits of layers
Wired and wireless connections
Encryption
IP addressing and MAC addressing
Standards
Common protocols
- TCP/IP (Transmission Control Protocol/Internet Protocol) – the basic set of rules that governs how data is sent across the internet.
- HTTP (Hyper Text Transfer Protocol) – used to transfer web pages.
- HTTPS (Hyper Text Transfer Protocol Secure) – like HTTP, but the data is encrypted for security.
- FTP (File Transfer Protocol) – used to transfer files between computers.
- POP (Post Office Protocol), IMAP (Internet Message Access Protocol) – used to receive email.
- SMTP (Simple Mail Transfer Protocol) – used to send email.
| Protocol | Purpose |
|---|---|
| TCP/IP Transmission Control Protocol/Internet Protocol | The underlying rules for how data is broken up, addressed, transmitted and reassembled across the internet. |
| HTTP Hyper Text Transfer Protocol | Transfers web pages between a web server and a browser. |
| HTTPS Hyper Text Transfer Protocol Secure | Same purpose as HTTP, but the data is encrypted for secure transfer. |
| FTP File Transfer Protocol | Transfers files between computers on a network. |
| POP / IMAP Post Office Protocol / Internet Message Access Protocol | Used by an email client to retrieve/receive email from a mail server. |
| SMTP Simple Mail Transfer Protocol | Used to send email (from a device to a mail server, and between mail servers). |
The concept of layers
Exam Phrasing: Use These Exact Phrases
- ✓Wired connections are generally faster and more secure but restrict mobility
- ✓Wireless connections allow mobility and easier connection of more devices, but are generally slower and less secure
- ✓Encryption scrambles data using a key so it cannot be understood if intercepted
- ✓An IPv4 address is four numbers from 0 to 255 separated by full stops
- ✓An IPv6 address is written as groups of hexadecimal digits separated by colons
- ✓A MAC address is a unique identifier permanently assigned to a device's network hardware
- ✓A standard is a set of agreed rules that allows hardware and software from different manufacturers to work together
- ✓A protocol is a set of rules for transferring data between devices
- ✓Different protocols are used for different purposes, e.g. HTTP for web pages, SMTP for sending email
- ✓Layers allow one layer to be changed without affecting the other layers
- 💡When comparing wired and wireless, avoid restating the same point twice in different words, "more secure" and "less likely to be intercepted" are one point, not two.
- 💡For "recommend a connection" questions, justify your answer using details from the specific scenario given, not just generic facts about wired/wireless.
- 💡Remember data is encrypted and decrypted using a key, not a "lock", precise terminology matters.
- 💡Match each protocol to its purpose precisely: SMTP sends email; POP and IMAP receive it.
- 💡Learn what each acronym stands for, not just what it does, questions sometimes ask you to give the full name (e.g. FTP = File Transfer Protocol).
- 💡You don't need to name or describe each individual TCP/IP layer, focus on the benefit: layers can be changed independently of each other.
Wrong:
Encryption uses a "lock" to scramble data
Right:
Encryption uses a key to scramble (and unscramble) data
Why it matters: OCR examiners specifically flagged "lock" as a common incorrect term where "key" was required.
Wrong:
Encryption stops data being intercepted
Right:
Encryption does not prevent interception at all: the data can still be intercepted, but without the key it is meaningless to whoever takes it
Why it matters: OCR examiners flagged this in more than one mark scheme. Encryption protects the data once taken, it does not stop the taking.
Wrong:
An IPv6 address uses 6 groups of numbers separated by full stops
Right:
An IPv6 address uses groups of hexadecimal digits separated by colons
Why it matters: Confusing IPv6 formatting with IPv4-style full stops, or assuming "6" in IPv6 refers to 6 groups, are common errors.
Wrong:
Recommending wireless "instead of" wired when a question asks for the benefit of adding wireless "as well as" wired
Right:
Read carefully whether the scenario is replacing wired or adding wireless alongside it
Why it matters: Misreading this changes the whole answer, examiners noted this as a common misunderstanding.
Wrong:
A standard is a specific product or piece of software
Right:
A standard is a set of agreed rules that allows different products to work together
Why it matters: Standards are principles/rules, not a specific technology, you don't need to know individual named standards.
Question:
An airport is upgrading its network to include wireless connections, in addition to its existing wired connections. Explain one benefit of including wireless connections. [2]
💡 Attempt this before revealing the answer, practice makes perfect!
Model Answer:
One benefit is that staff would be able to move around different areas of the airport while staying connected to the network, for example allowing them to track luggage or report problems from wherever they are, rather than being restricted to a fixed wired connection point.
Mark Scheme:
- 1Identifies mobility / ability to move around while connected as the benefit
- 2Applies this specifically to the airport scenario (e.g. staff moving around, tracking luggage)
Tap a card to flip it. Use the arrow keys to move and space to flip.
Exam-style questions. Have a go, then reveal the mark scheme to check your answer.
1.State one benefit of a wired connection compared to a wireless connection.
[1]2.State the purpose of a MAC address.
[1]3.Explain what is meant by encryption.
[2]4.A company wants to send an important document to a client, and it must remain confidential if intercepted during transmission. Explain how encryption would help achieve this.
[3]5.Explain why network protocols are organised into layers, rather than as one single set of rules.
[3]6.A user opens a webmail site in their browser, writes a message and sends it. Name the protocol used to load the web page securely, and the protocol used to send the message. Give the full name of each.
[4]7.A warehouse uses handheld scanners that staff carry around the building, and office computers that stay on the same desk all day. Recommend a connection type for each, justifying your answer with reference to the scenario.
[4]8.Discuss why computer networks use protocols arranged in layers, and the benefits this brings.
[8]Extended response · marked in levels, not by counting points
The examiners' reports are the most useful and least read of the three: they say what candidates actually got wrong each year. All files are hosted by OCR.
Past-paper questions grouped by topic
The same OCR questions, sorted by topic rather than by year (via Physics & Maths Tutor).
On a question about the benefits of a wired connection in an airport scenario, candidates could often identify a benefit but did not always explain why it mattered in that specific context, for example repeating "more secure" and "less likely to be intercepted" as if they were two separate points, when they are the same point.
On a question about adding wireless connections alongside existing wired ones, some candidates misread the question as asking about replacing wired connections entirely, and a common inaccurate claim was that wireless is always cheaper, when adding wireless as well as wired is an extra cost, not a saving.
On a question giving example IP addresses, a common IPv4 error was using numbers greater than 255; a common IPv6 error was giving only 6 groups of numbers, or separating groups with full stops instead of colons.
On a question matching protocols to tasks, HTTP and HTTPS were the most commonly and correctly identified. Protocols for other tasks, such as sending email, were less reliably known, know that SMTP is for sending email, and POP/IMAP are for receiving it.
On a question about why protocols use layers, most candidates showed some understanding of what a layer was, but fewer could explain why layers are used. The key point examiners wanted was that layers are independent, so one layer can be changed without needing to change or impact the others.