Computer Networks: Revision and References
Shared revision, practice questions, answer explanations and references from the original module.
By Akhilesh Saini
Module CA-07 — Consolidated quick revision
Use the table below for last-minute review, after understanding the explanations. Each row intentionally gives the simplest correct exam clue, not a substitute for real configuration details.
| Topic or clue | Core answer | Important qualification |
|---|---|---|
| Connected devices sharing resources | Computer network | Internet not required |
| Personal devices close to a person | PAN | Often Bluetooth, not exclusively |
| Office/building network | LAN | May use copper, fibre or Wi-Fi |
| Wireless LAN | WLAN | Wi-Fi is common; Internet is separate |
| City-scale connection | MAN | Approximate coverage classification |
| Distant connected branches | WAN | Need not be the public Internet |
| Central switch and spoke links | Star topology | Central device can be a failure point |
| Single traditional backbone | Bus topology | Historical shared-medium example |
| Closed loop | Ring topology | Implementations can differ in resilience |
| Multiple alternate links | Mesh topology | Full versus partial mesh |
| Branching hierarchy | Tree topology | Sometimes described as hierarchical star |
| Combination of patterns | Hybrid topology | Depends on constituent designs |
| Legacy Ethernet multiport repeater | Hub | Repeats without selective MAC forwarding |
| Link-layer frame forwarding | Switch | Usually uses learned MAC information |
| Inter-network IP forwarding | Router | Uses IP routing information |
| Signal regeneration | Repeater | Not an IP router |
| Modulation/demodulation function | Modem | Physical systems vary |
| Local exit or protocol translation | Gateway | Meaning depends on context |
| Wireless LAN attachment | Access point | Can exist without Internet connectivity |
| Copper twisted-pair cable | UTP / twisted pair | Ethernet also works over fibre |
| Glass/plastic light-guiding medium | Optical fibre | Resistant to ordinary EMI |
| Concentric conductor/shield cable | Coaxial | Common in cable access; legacy Ethernet |
| IPv4 length | 32 bits | Dotted-decimal notation |
| IPv6 length | 128 bits | Colon-separated hex notation |
| Typical Ethernet MAC length | 48 bits | Can be locally administered/randomized |
| IP address leasing/configuration | DHCP | Behaviour/configuration varies |
| Local IPv4-to-MAC resolution | ARP | IPv6 uses neighbour discovery instead |
| Web content exchange | HTTP | HTTPS adds TLS-based protection |
| HTTP over a protected connection | HTTPS | No guarantee website content is honest |
| Classic file-transfer protocol | FTP | Plain FTP is not secure by default |
| Send/relay email | SMTP | Common mail submission/relay protocol |
| Download-oriented mail retrieval | POP3 | Server retention can be configurable |
| Synchronize mailbox state | IMAP | Access across devices |
| Reliable ordered byte stream | TCP | Does not itself encrypt content |
| Internet packet addressing | IP | Does not guarantee delivery |
| WLAN using IEEE 802.11 | Wi-Fi | Local-network technology |
| Short-range peripheral connection | Bluetooth | PAN example |
| Close contactless communication | NFC | 13.56 MHz; not all digital payments |
| Provider-managed wide-area radio | Cellular network | 2G/3G/4G/5G are generations |
| Camera-scanned matrix code | QR code | Optical, not NFC radio |
Final self-check: ten essential distinctions
- Network vs Internet: Connected devices can share local resources without a live public Internet link.
- LAN vs WLAN: WLAN is a wireless local-network arrangement, not the complete Internet.
- WAN vs Internet: A WAN can join private business sites; Internet is a broader global system.
- Star vs bus: Star has a central device; bus shares a common backbone.
- Switch vs router: Typical switch forwards local frames using MAC information; router forwards among IP networks.
- Modem vs access point: A modem interfaces with a communications medium; a Wi-Fi access point provides wireless LAN access.
- Fibre vs copper: Fibre carries light; copper carries electrical signals.
- IPv4 vs MAC: IPv4 is 32-bit IP addressing; a common Ethernet MAC is 48-bit link-layer addressing.
- SMTP vs POP3/IMAP: SMTP sends/relays; POP3 and IMAP access incoming mailbox data.
- Wi-Fi vs Bluetooth vs NFC vs cellular: Local wireless networking, personal devices, close contactless radio, and operator wide-area radio serve different typical purposes.
Sources and further reading
The content above is original educational explanation. The following authoritative primary/technical resources support definitions and provide optional deeper reading. They are not substitutes for the introductory teaching in this module.
- Cisco — Networking basics — common building blocks: switches, routers, access points and network sharing.
- Cisco — Network switch versus router — different forwarding roles.
- Cisco — How does a switch work? — selective switching compared with hub behaviour.
- Cisco — What is a network gateway? — gateway role, including protocol translation.
- MDN — Overview of HTTP — requests, responses, clients and servers.
- RFC 791 — Internet Protocol — the IPv4 protocol.
- RFC 8200 — Internet Protocol, Version 6 — IPv6.
- RFC 1918 — Address Allocation for Private Internets — private IPv4 ranges.
- RFC 5737 — IPv4 Address Blocks Reserved for Documentation —
192.0.2.0/24and other example blocks. - RFC 3849 — IPv6 Address Prefix Reserved for Documentation —
2001:db8::/32example range. - RFC 9293 — Transmission Control Protocol — TCP's transport model.
- RFC 9051 — Internet Message Access Protocol — IMAP.
- NFC Forum — NFC Technology — contactless communication and 13.56 MHz fundamentals.
- IEEE 802.11 Wireless LAN Working Group — wireless LAN standard family.
- Bluetooth SIG — Bluetooth Technology — Bluetooth use and standards overview.