Internet and Networking Notes for SSC Exams
Rahul Kumar
SSC Exam Expert & Content Editor
Updated 03 Oct 2026
In this note
- 1.Internet Basics
- 2.IP Address and MAC Address
- 3.Types of Networks
- 4.Network Topologies
- 5.Network Devices
- 6.Transmission Media
- 7.Protocols
- 8.OSI Model and TCP/IP Model
- 9.Mobile Communication Generations
- 10.Email and Cloud Computing
- 11.Internet Security
- 12.E-Governance and Digital Services in India
- 13.Practice Questions With Answers
Internet and networking is one of the most important parts of computer awareness. Questions are asked on IP addresses, protocols, network devices, topologies, the OSI model, transmission media, mobile generations and basic internet terms. These Internet and Networking notes explain every topic in simple language with tables for quick revision.
Internet Basics
- The internet is a worldwide network of connected computer networks. It started from ARPANET, developed in the USA in 1969.
- The World Wide Web (WWW) is a collection of web pages that are accessed using the internet. It was invented by Tim Berners-Lee around 1989 to 1991. The internet is the network, and the web is a service that runs on it.
- A web page is a single document, a website is a collection of web pages, and the home page is the first page of a website.
- A browser (Chrome, Firefox, Edge, Safari, Opera) is software to view web pages. A search engine (Google, Bing, DuckDuckGo) finds information on the web.
- An ISP (Internet Service Provider) gives you internet access. Bandwidth is the amount of data that can be transferred per second and is measured in bits per second (bps).
URL and Domain Names
A URL has the format protocol://domain-name/path, for example https://www.ssceducation.com/notes. The part after the last dot of a domain is called the top-level domain.
| Domain | Meaning | Domain | Meaning |
|---|---|---|---|
| .com | Commercial | .org | Organisation |
| .edu | Educational institution (USA) | .gov | Government (USA) |
| .net | Network | .in | India |
| .gov.in | Indian government | .ac.in | Indian academic institution |
IP Address and MAC Address
- An IP address is a unique number that identifies a device on a network. IPv4 uses 32 bits (four numbers from 0 to 255, such as 192.168.1.1). IPv6 uses 128 bits and is written in hexadecimal.
- The DNS (Domain Name System) converts a domain name into an IP address. DHCP gives IP addresses automatically.
- A MAC address is a 48-bit hardware address stored in the Network Interface Card (NIC) and it is fixed for the device.
- The loopback address 127.0.0.1 refers to the computer itself.
IPv4 Classes
| Class | First octet range | Use |
|---|---|---|
| A | 1 to 126 | Very large networks |
| B | 128 to 191 | Medium networks |
| C | 192 to 223 | Small networks |
| D | 224 to 239 | Multicasting |
| E | 240 to 255 | Experimental |
Types of Networks
| Type | Full form | Example / range |
|---|---|---|
| PAN | Personal Area Network | Bluetooth, a few metres |
| LAN | Local Area Network | Office or school, up to a few km |
| MAN | Metropolitan Area Network | A city, cable TV network |
| WAN | Wide Area Network | Country or world; the internet is the largest WAN |
| WLAN | Wireless LAN | Wi-Fi network |
- Intranet is a private network inside an organisation, Extranet allows limited access to outsiders such as customers, and the Internet is open to all.
- Client-server: a server provides services and clients use them. Peer-to-peer: all computers have equal roles.
Network Topologies
| Topology | Structure | Advantage / Disadvantage |
|---|---|---|
| Bus | One main cable | Cheap, but failure of the cable stops the network |
| Star | All devices connect to a central hub or switch | Easy to add devices; failure of the hub stops the network |
| Ring | Devices form a closed loop | Equal access; one break can stop the network |
| Mesh | Every device connects to every other | Most reliable but expensive |
| Tree | Star networks joined by a bus | Scalable but complex |
| Hybrid | Combination of two or more topologies | Flexible and large networks |
Network Devices
| Device | Function |
|---|---|
| Modem | Converts digital signals to analog and back for telephone lines |
| Hub | Sends data to all connected devices |
| Switch | Sends data only to the correct device using MAC addresses |
| Router | Connects different networks and finds the best path for data using IP addresses |
| Bridge | Connects two similar LANs |
| Gateway | Connects networks with different protocols |
| Repeater | Regenerates a weak signal |
| Access Point | Provides Wi-Fi to wireless devices |
| NIC | Network card that connects a computer to a network |
Transmission Media
- Guided (wired): twisted pair cable (telephone and LAN), coaxial cable (cable TV) and optical fibre, which carries data as light and gives the highest speed and security.
- Unguided (wireless): radio waves, microwaves, infrared and satellite communication.
- Bluetooth is short-range wireless technology. Wi-Fi is a wireless LAN technology. NFC works at a distance of a few centimetres.
Protocols
| Protocol | Purpose |
|---|---|
| HTTP / HTTPS | Transfer of web pages (HTTPS is secure and uses SSL/TLS) |
| FTP | Uploading and downloading files |
| SMTP | Sending email |
| POP3 / IMAP | Receiving email |
| TCP | Reliable delivery of data in packets |
| UDP | Fast but unreliable delivery (video, gaming) |
| IP | Addressing and routing of packets |
| DNS | Converts domain names into IP addresses |
| DHCP | Assigns IP addresses automatically |
| Telnet / SSH | Remote login (SSH is secure) |
| VoIP | Voice calls over the internet |
OSI Model and TCP/IP Model
| Layer no. | OSI layer | Data unit | Main work |
|---|---|---|---|
| 7 | Application | Data | Services to the user (HTTP, FTP, SMTP) |
| 6 | Presentation | Data | Translation, encryption and compression |
| 5 | Session | Data | Starts, manages and ends sessions |
| 4 | Transport | Segment | End-to-end delivery (TCP, UDP) |
| 3 | Network | Packet | Addressing and routing (IP, router) |
| 2 | Data Link | Frame | Error detection, MAC address (switch) |
| 1 | Physical | Bits | Transmission of raw bits through cables and signals |
The TCP/IP model has four layers: Application, Transport, Internet and Network Access. The TCP/IP model is the practical model used on the internet, while the OSI model is a reference model.
Mobile Communication Generations
| Generation | Technology / Feature |
|---|---|
| 1G | Analog voice calls |
| 2G | Digital voice, SMS (GSM, CDMA) |
| 3G | Mobile internet and video calls |
| 4G | High-speed broadband (LTE) |
| 5G | Very high speed, very low delay, IoT and smart cities |
Email and Cloud Computing
- An email address has the format username@domain. Fields: To, Cc (carbon copy, visible to all) and Bcc (blind carbon copy, hidden).
- Cloud computing provides computing services over the internet. Types of service: IaaS (infrastructure), PaaS (platform) and SaaS (software). Deployment models: public, private, hybrid and community cloud.
- Examples: Google Drive, OneDrive, Dropbox and iCloud for storage.
Internet Security
- A firewall monitors and filters network traffic. A proxy server acts as a middleman between the user and the internet. A VPN creates a secure private connection over the internet.
- HTTPS and the padlock sign show an encrypted connection. Cookies are small files that websites store in the browser.
- Common threats are phishing, malware, ransomware, DDoS attacks and identity theft. Use strong passwords and two-factor authentication.
E-Governance and Digital Services in India
- Digital India was launched in 2015. DigiLocker stores digital documents, UMANG gives many government services in one app, and UPI and BHIM allow instant digital payments.
- E-commerce means buying and selling online, and e-learning means learning through the internet.
Practice Questions With Answers
- The origin of the internet is: Answer: ARPANET
- The length of an IPv4 address is: Answer: 32 bits
- Which device connects different networks? Answer: Router
- Which topology uses a central hub or switch? Answer: Star
- Which protocol is used to send email? Answer: SMTP
- Which layer of the OSI model is responsible for routing? Answer: Network layer
- How many layers are there in the OSI model? Answer: 7
- Which transmission medium is the fastest? Answer: Optical fibre
- Which technology is called the fourth generation of mobile communication? Answer: LTE (4G)
- Which address is stored in the NIC? Answer: MAC address
- Which class of IP address begins with 192 to 223? Answer: Class C
- What converts a domain name into an IP address? Answer: DNS
Revise the abbreviations from Computer Full Forms, and read the complete Computer Knowledge Notes for the full syllabus. Test yourself with our previous year papers.
About the Author
Rahul Kumar
SSC Exam Expert & Content Editor
Rahul is a senior SSC exam strategist with 8+ years of experience helping aspirants crack CGL, CHSL and MTS exams. He writes in-depth notification breakdowns, exam pattern guides and preparation strategies.