Course outline
Module 1
Module 1: Introduction to Networks
Introduction to Networks
Knowledge check
Q1. What is the primary purpose of a computer network?
- A. To permanently store data on a single computer
- B. To allow devices to share resources and communicate with each other ✓
- C. To increase the processing speed of a single computer
- D. To replace the need for operating systems
Why: A computer network connects devices so they can share resources such as files, printers, and internet access, and communicate with one another.
Q2. Which term describes a network that covers a small geographic area such as a home, office, or single building?
- A. WAN
- B. MAN
- C. LAN ✓
- D. PAN
Why: A Local Area Network (LAN) covers a limited area like a home, office, or building. WANs span large distances, MANs cover a city, and PANs cover very short personal ranges.
Q3. What is the role of a router in a network?
- A. To connect devices within the same local network only
- B. To amplify wireless signals in a building
- C. To forward data packets between different networks ✓
- D. To assign file names to stored data
Why: A router forwards data packets between networks, such as between your home LAN and the internet, by determining the best path for the data to travel.
Q4. What does the term 'bandwidth' refer to in networking?
- A. The physical length of a network cable
- B. The maximum amount of data that can be transmitted over a connection in a given time ✓
- C. The number of devices connected to a network
- D. The security level of a network connection
Why: Bandwidth is the maximum rate at which data can be transferred over a network connection, usually measured in bits per second (bps).
Q5. Which of the following is an example of a client-server network model?
- A. Several computers sharing files directly with each other without a central host
- B. A web browser on your laptop requesting a webpage from a web server ✓
- C. A single computer that is not connected to any other device
- D. Two phones communicating through Bluetooth only
Why: In the client-server model, client devices such as your laptop request services or data from a central server, such as a web server that hosts websites.
Module 2
Module 2: Network Devices and Topologies
Network Devices and Topologies
Knowledge check
Q1. Which network device forwards data packets between different networks based on IP addresses?
- A. Hub
- B. Switch
- C. Router ✓
- D. Repeater
Why: A router operates at the network layer (Layer 3) and uses IP addresses to determine the best path for forwarding packets between different networks, such as a home LAN and the internet.
Q2. What is the main difference between a hub and a switch?
- A. A hub sends data only to the intended recipient, while a switch broadcasts to all ports
- B. A switch sends data only to the intended recipient port using MAC addresses, while a hub broadcasts to all ports ✓
- C. A hub works at Layer 3 while a switch works at Layer 1
- D. There is no functional difference between a hub and a switch
Why: A switch learns the MAC addresses connected to each port and forwards frames only to the appropriate port, reducing collisions. A hub repeats incoming signals out of every port, creating a single collision domain.
Q3. Which network topology connects every device directly to a central device, such as a switch?
- A. Ring topology
- B. Bus topology
- C. Star topology ✓
- D. Mesh topology
Why: In a star topology, each device connects to a central point such as a switch or hub. This is the most common topology in modern local area networks because a failure of one cable affects only that single device.
Q4. What is a key disadvantage of a bus topology?
- A. It is very expensive to install
- B. A break in the main cable can bring down the entire network ✓
- C. It cannot support more than two devices
- D. It requires a dedicated router for every device
Why: All devices in a bus topology share a single backbone cable. If that cable is damaged or disconnected, communication across the entire network can fail, and the shared medium also limits performance as more devices are added.
Q5. Which device is used to extend the reach of a network signal by regenerating and retransmitting it?
- A. Repeater ✓
- B. Firewall
- C. Modem
- D. Bridge
Why: A repeater receives a weakened or attenuated signal, regenerates it, and retransmits it, allowing the signal to travel farther along the cable. It operates at the physical layer and does not filter or route traffic.
Module 3
Module 3: The OSI and TCP/IP Models
The OSI and TCP/IP Models
Knowledge check
Q1. How many layers does the OSI model contain?
Why: The OSI (Open Systems Interconnection) model is a conceptual framework that divides network communication into seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.
Q2. Which OSI layer is responsible for routing packets between different networks?
- A. Data Link layer
- B. Transport layer
- C. Network layer ✓
- D. Session layer
Why: The Network layer (Layer 3) handles logical addressing (such as IP addresses) and determines the best path for packets to travel from source to destination across multiple networks, which is the job of routers.
Q3. Which layer of the TCP/IP model corresponds to the combined functions of the OSI Physical and Data Link layers?
- A. Application layer
- B. Transport layer
- C. Internet layer
- D. Network Access layer ✓
Why: The TCP/IP model's Network Access (also called Link) layer covers both the OSI Physical and Data Link layers, handling hardware transmission and local frame delivery such as Ethernet.
Q4. Which protocol operates at the Transport layer of the TCP/IP model and provides reliable, connection-oriented delivery?
- A. UDP
- B. IP
- C. TCP ✓
- D. ICMP
Why: TCP (Transmission Control Protocol) is a connection-oriented transport protocol that guarantees ordered, reliable delivery through acknowledgments, retransmission, and flow control. UDP is connectionless and does not guarantee delivery.
Q5. What is the main purpose of encapsulation in the OSI model?
- A. Encrypting data so only the receiver can read it
- B. Compressing data to reduce bandwidth usage
- C. Adding header information from each layer as data moves down the stack ✓
- D. Splitting data into smaller pieces for the physical medium
Why: Encapsulation occurs as data moves down the layers of the sending device: each layer adds its own header (and sometimes trailer) containing control information needed by its peer layer on the receiving device.
Module 4
Module 4: IP Addressing and Subnetting
IP Addressing and Subnetting
Knowledge check
Q1. How many bits are in an IPv4 address?
- A. 16 bits
- B. 32 bits ✓
- C. 64 bits
- D. 128 bits
Why: An IPv4 address is 32 bits long, usually written as four 8-bit octets separated by dots. IPv6 addresses are 128 bits long.
Q2. Which of the following is a private IP address range defined in RFC 1918?
- A. 8.8.8.0 to 8.8.8.255
- B. 172.16.0.0 to 172.31.255.255 ✓
- C. 200.1.1.0 to 200.1.1.255
- D. 1.0.0.0 to 1.255.255.255
Why: RFC 1918 reserves 10.0.0.0/8, 172.16.0.0/12 (172.16.0.0 to 172.31.255.255), and 192.168.0.0/16 for private use. The other ranges shown are public addresses routable on the internet.
Q3. What is the subnet mask 255.255.255.0 written in CIDR notation?
- A. /16
- B. /20
- C. /24 ✓
- D. /28
Why: The subnet mask 255.255.255.0 has 24 consecutive 1 bits (three full octets of 255), so its CIDR notation is /24.
Q4. How many usable host addresses are available in a /24 network?
- A. 254 ✓
- B. 256
- C. 255
- D. 512
Why: A /24 network has 2^8 = 256 total addresses. Two are reserved: the network address (all host bits 0) and the broadcast address (all host bits 1), leaving 254 usable host addresses.
Q5. Which address is the network address for the host 192.168.10.37 in a 255.255.255.0 subnet?
- A. 192.168.10.0 ✓
- B. 192.168.10.1
- C. 192.168.10.255
- D. 192.168.0.0
Why: The network address is found by ANDing the IP address with the subnet mask. Applying 255.255.255.0 to 192.168.10.37 keeps the first three octets and zeroes the last one, giving 192.168.10.0.
Module 5
Module 5: Routing and Switching Basics
Routing and Switching Basics
Knowledge check
Q1. What is the primary function of a router?
- A. To forward data between different networks based on IP addresses ✓
- B. To forward data within a single network based on MAC addresses
- C. To amplify wireless signals across a building
- D. To assign domain names to devices on a network
Why: A router connects different networks and forwards packets between them using IP addresses, determining the best path to the destination network.
Q2. Which device operates at Layer 2 of the OSI model and forwards frames based on MAC addresses?
- A. Hub
- B. Router
- C. Switch ✓
- D. Repeater
Why: A switch operates at Layer 2 (Data Link layer) and uses MAC address tables to forward frames only to the port where the destination device is connected.
Q3. What does a switch do when it receives a frame with a destination MAC address not yet in its MAC address table?
- A. It drops the frame silently
- B. It sends the frame back to the source
- C. It floods the frame out all ports except the one it arrived on ✓
- D. It forwards the frame to the default gateway
Why: When the destination is unknown, a switch floods the frame to all ports except the incoming port, and learns the correct port when the destination replies.
Q4. What is the purpose of a routing table?
- A. To store user login credentials for network access
- B. To list the known networks and the next hop or interface used to reach each one ✓
- C. To map domain names to IP addresses
- D. To record the MAC addresses of all connected devices
Why: A routing table contains entries for destination networks and tells the router which next hop or outgoing interface to use to reach each one.
Q5. Which statement best describes a default route?
- A. A route used only for multicast traffic
- B. A route that is used when no more specific route matches the destination ✓
- C. A route that always has the lowest metric in the table
- D. A route manually deleted after each reboot
Why: A default route (often written 0.0.0.0/0) matches any destination and is used when no more specific routing table entry exists, commonly pointing toward the internet gateway.
Module 6
Module 6: Common Protocols and Services
Common Protocols and Services
Knowledge check
Q1. Which protocol is primarily used to translate human-readable domain names into IP addresses?
- A. DHCP
- B. DNS ✓
- C. FTP
- D. SMTP
Why: DNS (Domain Name System) resolves domain names such as example.com into IP addresses that computers use to locate each other on a network. DHCP assigns IP addresses, FTP transfers files, and SMTP sends email.
Q2. Which well-known port number is used by HTTPS by default?
- A. 80
- B. 21
- C. 443 ✓
- D. 25
Why: HTTPS uses port 443 by default for encrypted web traffic. Port 80 is used for unencrypted HTTP, port 21 for FTP control, and port 25 for SMTP email transmission.
Q3. What does DHCP automatically provide to devices joining a network?
- A. Encryption keys for all websites
- B. A permanent domain name
- C. An IP address and other network configuration settings ✓
- D. A faster physical cable connection
Why: DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses, subnet masks, default gateways, and DNS server information to devices so they can communicate on the network without manual setup.
Q4. Which protocol is commonly used to send email from a client to a mail server?
- A. POP3
- B. IMAP
- C. SMTP ✓
- D. SNMP
Why: SMTP (Simple Mail Transfer Protocol) is used to send email messages from a client to a mail server and between mail servers. POP3 and IMAP are used to retrieve email, while SNMP is used for network device monitoring.
Q5. Which protocol is used to test whether a remote host is reachable and to measure round-trip time?
- A. ICMP (ping) ✓
- B. ARP
- C. HTTP
- D. Telnet
Why: ICMP (Internet Control Message Protocol) is used by the ping utility to send echo requests and receive echo replies, which tests reachability and latency. ARP maps IP addresses to MAC addresses, HTTP serves web content, and Telnet provides remote terminal access.
Module 7
Module 7: Network Security and Troubleshooting
Network Security and Troubleshooting
Knowledge check
Q1. Which tool is commonly used to check whether a remote host is reachable by sending ICMP echo requests?
- A. traceroute
- B. ping ✓
- C. netstat
- D. nslookup
Why: Ping sends ICMP echo request messages and waits for echo replies, which makes it the standard tool for testing basic reachability and round-trip latency to a host.
Q2. What is the main purpose of a firewall in a network?
- A. To assign IP addresses to devices automatically
- B. To translate domain names into IP addresses
- C. To filter incoming and outgoing traffic based on defined security rules ✓
- D. To store copies of frequently accessed web pages
Why: A firewall inspects network traffic and allows or blocks it according to security rules, helping protect internal systems from unauthorized access.
Q3. Which port is the default for HTTPS traffic?
- A. 80
- B. 21
- C. 443 ✓
- D. 25
Why: HTTPS uses TCP port 443 by default, while HTTP uses port 80, FTP uses port 21, and SMTP uses port 25.
Q4. A user can access websites by IP address but cannot load them by domain name. Which service is most likely failing?
- A. DHCP
- B. DNS ✓
- C. NAT
- D. ARP
Why: DNS resolves domain names to IP addresses. If IP access works but name-based access fails, the DNS resolution step is the most likely problem.
Q5. Which security practice best protects a wireless network from unauthorized access?
- A. Broadcasting the network name at all times
- B. Using WPA2 or WPA3 encryption with a strong passphrase ✓
- C. Leaving the router with its default administrator password
- D. Disabling the firewall to improve speed
Why: WPA2 and WPA3 provide strong encryption for wireless traffic, and a strong passphrase makes it harder for attackers to gain access. Default credentials and disabled firewalls weaken security.