Slide 1: Question 1

How many layers are there in the OSI network model?

A. 5
B. 6
C. 7
D. 8

Slide 2: Answer 1

Correct Answer: C. 7
The OSI (Open Systems Interconnection) model has seven layers. These range from the
Physical layer (Layer 1) at the bottom up to the Application layer (Layer 7) at the top. Each
layer has a specific role, and together they provide a framework for understanding how
different networking protocols interact.

Slide 3: Question 2

Which protocol provides a connectionless, unreliable transport service in the TCP/IP

suite?

A. TCP
B. UDP
C. HTTP
D. IP

Slide 4: Answer 2

Correct Answer: B. UDP

UDP (User Datagram Protocol) is a connectionless transport layer protocol in the Internet
protocol suite. It sends packets (datagrams) without establishing a dedicated connection and
without guarantees of delivery or order. This makes UDP faster and suitable for applications
like streaming or DNS queries, but less reliable than TCP (which is connection-oriented and
ensures delivery).

Slide 5: Question 3

Which routing algorithm suffers from the count-to-infinity problem due to its iterative
nature of sharing information with neighbors?

A. Link-state routing
B. Distance-vector routing
C. Static routing
D. Flooding algorithm
Slide 6: Answer 3

Correct Answer: B. Distance-vector routing

Distance-vector routing algorithms (such as RIP) periodically share their routing tables with
neighboring routers. This approach can lead to the count-to-infinity problem, where routers
increment route distances indefinitely in case of certain network failures (a symptom of
routing loops). Link-state algorithms, in contrast, avoid this issue by having a complete
network map and computing shortest paths (e.g., OSPF uses Dijkstra’s algorithm).

Slide 7: Question 4

Which switching technique establishes a dedicated communication path between two

endpoints for the duration of the session?

A. Packet switching
B. Circuit switching
C. Message switching
D. Cell switching

Slide 8: Answer 4

Correct Answer: B. Circuit switching

Circuit switching sets up a dedicated channel or circuit between the communicating parties
before data transmission begins. This path remains reserved (even if no data is being sent
momentarily) until the session ends. Traditional telephone networks use circuit switching,
providing a continuous connection but potentially wasting bandwidth when the channel is
idle.

Slide 9: Question 5

Which IPv6 address property distinguishes it from IPv4 addresses?

A. IPv6 addresses are 32 bits long.

B. IPv6 addresses are expressed in decimal.
C. IPv6 addresses consist of 128 bits.
D. IPv6 addresses use a dotted-decimal format.

Slide 10: Answer 5

Correct Answer: C. IPv6 addresses consist of 128 bits.

An IPv6 address is 128 bits long, in contrast to an IPv4 address which is 32 bits long. IPv6
addresses are usually written in hexadecimal and separated by colons (e.g., 2001:0db8:...),
whereas IPv4 addresses use the familiar 32-bit dotted-decimal format (e.g., 192.168.1.1). The
larger size of IPv6 addresses provides a vastly expanded address space.
Slide 11: Question 6

Which statement about analog and digital signals is correct?

A. Analog signals vary continuously, while digital signals use discrete levels (e.g., 0 and 1).
B. Analog signals use only 0s and 1s, digital signals vary over continuous values.
C. Digital signals are used only for audio, analog signals only for data.
D. Both analog and digital signals have an infinite number of possible values.

Slide 12: Answer 6

Correct Answer: A. Analog signals vary continuously, while digital signals use discrete
levels (e.g., 0 and 1).
Analog signals are continuous waveforms that can represent an infinite range of values, such
as the varying voltage of a sound wave. Digital signals, by contrast, have discrete states
(commonly 0 and 1). This means digital signals change in steps and are easier to regenerate
without error, whereas analog signals can degrade and pick up noise continuously.

Slide 13: Question 7

Which multiplexing technique allows multiple signals to share the same medium by
transmitting on different frequencies?

A. Time Division Multiplexing (TDM)

B. Frequency Division Multiplexing (FDM)
C. Code Division Multiple Access (CDMA)
D. Phase Division Multiplexing

Slide 14: Answer 7

Correct Answer: B. Frequency Division Multiplexing (FDM)

Frequency Division Multiplexing involves allocating separate frequency bands to each signal
on a shared medium. Each signal modulates a different carrier frequency, so multiple signals
can be transmitted simultaneously without interfering (as long as their frequency bands do
not overlap). Examples include radio and TV broadcasting, where different stations operate
on different frequency channels.

Slide 15: Question 8

Which type of cable consists of a central copper conductor surrounded by insulation

and a braided metal shield?
A. Twisted pair cable
B. Coaxial cable
C. Fiber optic cable
D. Ribbon cable

Slide 16: Answer 8

Correct Answer: B. Coaxial cable

Coaxial cable has a concentric design: a central copper core conductor, an insulating layer, a
metallic braided or foil shield, all encased in an outer insulating jacket. This construction
provides good shielding against electromagnetic interference. Coaxial cables are commonly
used for cable television, older Ethernet networks (10BASE2/10BASE5), and other RF signal
transmission.

Slide 17: Question 9

Which of the following techniques is used only for error detection (and not for error
correction)?

A. Parity check
B. Hamming code
C. Reed-Solomon code
D. Forward error correction (FEC)

Slide 18: Answer 9

Correct Answer: A. Parity check

A parity check (adding a parity bit) is a simple error-detection technique. It can detect certain
errors (e.g., any single-bit error in the case of odd or even parity) but cannot correct them. In
contrast, Hamming codes and Reed-Solomon codes are error-correcting codes (they add
redundant bits to allow the correction of errors at the receiver). Forward Error Correction is a
category of methods that includes codes like Hamming and Reed-Solomon, which can both
detect and correct errors without requiring retransmission.

Slide 19: Question 10

Flow control in data communication is primarily used to:

A. Prevent a fast sender from overwhelming a slow receiver with data.

B. Avoid collisions on a shared communication medium.
C. Route packets along the shortest path.
D. Encrypt data during transmission.

Slide 20: Answer 10

Correct Answer: A. Prevent a fast sender from overwhelming a slow receiver with data.
Flow control mechanisms (such as sliding window protocols) regulate the rate of data
transmission between a sender and receiver. This ensures that the sender does not send data
faster than the receiver (and its buffers) can process it. By preventing receiver overrun, flow
control maintains reliable communication. (Avoiding collisions on a medium is handled by
MAC protocols, and routing and encryption are unrelated to flow control.)

Slide 21: Question 11

Which networking device operates at the OSI Network layer (Layer 3) and routes
packets between different networks?

A. Switch
B. Router
C. Hub
D. Bridge

Slide 22: Answer 11

Correct Answer: B. Router

A router operates at the Network layer of the OSI model. It uses logical addressing (IP
addresses) to make forwarding decisions, routing packets from one network to another.
Switches and bridges operate at the Data Link layer (using MAC addresses), and hubs
operate at the Physical layer (simply repeating signals). Routers enable internetworking by
connecting multiple LANs or subnetworks and directing traffic toward its destination
network.

Slide 23: Question 12

What type of network is typically confined to a single building or campus, connecting

computers in a small geographic area?

A. WAN (Wide Area Network)

B. MAN (Metropolitan Area Network)
C. PAN (Personal Area Network)
D. LAN (Local Area Network)

Slide 24: Answer 12

Correct Answer: D. LAN (Local Area Network)

A Local Area Network (LAN) covers a limited area such as an office, building, or campus.
LANs usually are owned and managed by a single organization and typically use high-speed
connections (like Ethernet or Wi-Fi) to connect computers and peripherals. In contrast,
MANs span a city or metro area, WANs cover large geographical regions (country or globe),
and PANs refer to very short-range networks (like Bluetooth connections around an
individual).

Slide 25: Question 13

What is the main function of DNS (Domain Name System) in networking?

A. Translating human-readable domain names into IP addresses.

B. Mapping MAC addresses to IP addresses in a local network.
C. Establishing a secure encrypted connection between client and server.
D. Assigning dynamic IP addresses to hosts on a network.

Slide 26: Answer 13

Correct Answer: A. Translating human-readable domain names into IP addresses.

The Domain Name System (DNS) resolves domain names (like example.com) into their
numeric IP addresses. This is crucial because users prefer memorable domain names, while
network routing uses IP addresses. Options B and D describe functions of ARP and DHCP,
respectively, and C refers to protocols like TLS/SSL. DNS servers collectively form a
distributed database that allows any hostname to be translated to the correct IP address for
connectivity.

Slide 27: Question 14

Which of the following is a symmetric-key encryption algorithm?

A. AES
B. RSA
C. Diffie-Hellman
D. SHA-256

Slide 28: Answer 14

Correct Answer: A. AES

AES (Advanced Encryption Standard) is a symmetric encryption algorithm, meaning it uses
the same secret key for encryption and decryption. In contrast, RSA and Diffie-Hellman are
asymmetric techniques (RSA is an encryption algorithm using a public/private key pair, and
Diffie-Hellman is a key exchange method). SHA-256 is a hashing algorithm (one-way, not
used for encrypting/decrypting data). Symmetric algorithms like AES are generally faster for
bulk data encryption.

Slide 29: Question 15

What does GSM stand for in mobile communications?

A. Global System for Mobile Communications

B. General Satellite Module
C. Google Sync Manager
D. Global Signal Multiplexing

Slide 30: Answer 15

Correct Answer: A. Global System for Mobile Communications

GSM is an acronym for Global System for Mobile Communications. It is a standard
developed for 2G digital cellular networks, first deployed in Europe and now used
worldwide. GSM introduced SIM cards and digital modulation (TDMA/FDMA) for voice
communication and texting. The other options are incorrect expansions.

Slide 31: Question 16

Which of the following is a key characteristic of cloud computing that benefits

organizations?

A. The ability to rapidly scale resources up or down based on demand.

B. Requirement to purchase and maintain all hardware internally.
C. Users must manually manage all network infrastructure in the cloud.
D. Eliminates the need for data backups entirely.

Slide 32: Answer 16

Correct Answer: A. The ability to rapidly scale resources up or down based on demand.
A major advantage of cloud computing is elasticity – resources (compute power, storage,
etc.) can be provisioned and released on-demand, scaling to match workload needs. This pay-
as-you-go model reduces the need for heavy upfront hardware investments (contrary to
option B) and offloads much infrastructure management to the cloud provider (contrary to C).
Data backups are still important in the cloud (option D is false), although many cloud
services include managed backup and redundancy by default.

Slide 33: Question 17

Which OSI layer is responsible for routing packets between networks and handling
logical addressing?

A. Data Link layer

B. Network layer
C. Transport layer
D. Application layer
Slide 34: Answer 17

Correct Answer: B. Network layer

The Network layer (Layer 3 of OSI) is in charge of path determination and logical
addressing. It routes packets across different networks by examining destination IP addresses
and deciding the best route. This layer is exemplified by protocols like IP. The Data Link
layer (Layer 2) deals with local, physical network addressing (MAC addresses) on the same
network segment, while the Transport layer handles end-to-end transport (e.g., TCP/UDP)
and the Application layer deals with high-level protocols like HTTP, FTP, etc.

Slide 35: Question 18

Which protocol in the TCP/IP suite is responsible for logical addressing and routing of
packets across networks?

A. TCP
B. ARP
C. IP
D. DHCP

Slide 36: Answer 18

Correct Answer: C. IP
The Internet Protocol (IP) is the core network-layer protocol in the TCP/IP suite. It provides
logical addressing (IP addresses) and is responsible for routing packets from a source to a
destination across one or more networks. TCP is a transport-layer protocol (ensures reliable
delivery), ARP maps IP addresses to MAC addresses on a local network, and DHCP
dynamically assigns IP addresses to hosts. IP itself defines how packets are structured and
transported, enabling internetworking between different physical networks.

Slide 37: Question 19

RIP (Routing Information Protocol) is an example of which type of routing

algorithm/protocol?

A. Link-state
B. Distance-vector
C. Path-vector
D. Hybrid

Slide 38: Answer 19

Correct Answer: B. Distance-vector

RIP is a classic distance-vector routing protocol. It operates by having routers periodically
exchange their entire routing tables with immediate neighbors. Distance-vector protocols
(like RIP) use metrics such as hop count and are prone to issues like count-to-infinity without
loop prevention techniques. Link-state protocols (like OSPF) instead flood link-state
information and build a topology map, and path-vector is used by BGP. RIP’s simplicity and
use of hop count (max 15) classify it firmly as a distance-vector protocol.

Slide 39: Question 20

Which routing protocol is based on a link-state algorithm, using knowledge of the entire
network topology to compute routes?

A. OSPF
B. RIP
C. BGP
D. EIGRP

Slide 40: Answer 20

Correct Answer: A. OSPF

OSPF (Open Shortest Path First) is a link-state routing protocol. Each OSPF router floods
information about its links (adjacencies and costs) to all other routers in the OSPF area. Using
this complete topology information, each router independently calculates the shortest path to
every network (often via Dijkstra’s algorithm). RIP is distance-vector, BGP is a path-vector
(used between autonomous systems), and EIGRP (by Cisco) is often considered a hybrid but
fundamentally distance-vector with some link-state features.

Slide 41: Question 21

Which switching method involves storing an entire message at each intermediate node
before forwarding it to the next node?

A. Packet switching
B. Circuit switching
C. Message switching
D. Cut-through switching

Slide 42: Answer 21

Correct Answer: C. Message switching

In message switching, the whole message is received and stored at an intermediate switch or
node before being forwarded. This store-and-forward approach means that a large message
must be fully accumulated before moving on, potentially introducing significant delays.
Packet switching, by contrast, breaks data into smaller packets that are forwarded as soon as
they arrive (without waiting for a whole large message). Circuit switching establishes a
dedicated path, and cut-through switching is a method used in some packet-switched network
devices (like switches) to begin forwarding before the entire frame is received.
Slide 43: Question 22

Which OSI layer provides physical (hardware) addresses and is responsible for
delivering frames on the local network segment?

A. Physical layer
B. Data Link layer
C. Network layer
D. Session layer

Slide 44: Answer 22

Correct Answer: B. Data Link layer

The Data Link layer (Layer 2 of OSI) is responsible for node-to-node delivery on the same
network. It uses physical addresses (MAC addresses) to identify source and destination
within a local segment and packages data into frames. This layer also typically handles error
detection for frames (e.g., CRC) and flow control on the link. The Physical layer (Layer 1)
moves raw bits, Network layer handles logical addressing/routing, and Session layer manages
interhost communication sessions.

Slide 45: Question 23

A modem is used in networking to:

A. route data between local networks.

B. convert digital signals to analog and vice versa.
C. amplify and regenerate signals at the bit level.
D. assign IP addresses to devices.

Slide 46: Answer 23

Correct Answer: B. Convert digital signals to analog and vice versa.

A modem (short for modulator-demodulator) converts digital data from a computer into
analog signals that can be transmitted over analog communication lines (like traditional
telephone lines), and it converts incoming analog signals back into digital data. For example,
dial-up and DSL modems enable data transmission over phone lines by modulating digital
data into audio frequencies and demodulating the received signals. Modems do not perform
routing or IP assignment; those are the roles of routers and DHCP servers, respectively.
Repeaters amplify/regenerate signals, but they don't modulate/demodulate.

Slide 47: Question 24

In frequency modulation (FM), which characteristic of the carrier wave is varied to
encode the information signal?

A. Amplitude of the carrier

B. Frequency of the carrier
C. Phase of the carrier
D. Duration of each bit interval

Slide 48: Answer 24

Correct Answer: B. Frequency of the carrier

Frequency Modulation (FM) works by varying the frequency of the carrier wave in
proportion to the input (information) signal, while the amplitude remains constant. By
contrast, in Amplitude Modulation (AM), the amplitude of the carrier is varied according to
the information signal (frequency remains constant), and in Phase Modulation (PM), the
phase of the carrier is altered. FM is widely used in radio broadcasting (e.g., FM radio)
because it is more resistant to amplitude noise.

Slide 49: Question 25

What term describes the range of frequencies that a communication channel can carry?

A. Latency
B. Bandwidth
C. Throughput
D. Noise floor

Slide 50: Answer 25

Correct Answer: B. Bandwidth

Bandwidth is the range of frequencies that a channel can transmit, typically measured in hertz
(Hz). For example, a channel might carry frequencies from 1 MHz to 5 MHz, giving it a
bandwidth of 4 MHz. In networking, we often loosely use "bandwidth" to also mean data rate
(bits per second) because a higher frequency bandwidth generally allows higher data
throughput. Latency is a time delay measure, throughput is the actual achieved data transfer
rate, and noise floor refers to the level of background interference.

Slide 51: Question 26

Which multiplexing technique is commonly used in fiber-optic communications to send

multiple signals on a single fiber?

A. FDM (Frequency Division Multiplexing)

B. TDM (Time Division Multiplexing)
C. WDM (Wavelength Division Multiplexing)
D. CDMA (Code Division Multiple Access)

Slide 52: Answer 26

Correct Answer: C. Wavelength Division Multiplexing (WDM)

WDM is essentially FDM applied to optical communication: it combines multiple optical
carrier signals on a single fiber by using different wavelengths (colors) of laser light for each
signal. This allows a single fiber to carry multiple data streams simultaneously. For instance,
Dense WDM is used in fiber backbones to greatly increase capacity. TDM splits time slots
for signals, and CDMA uses coding; while FDM is similar to WDM in concept, WDM is the
specific term for wavelength-based multiplexing in fiber optics.

Slide 53: Question 27

Which of the following is NOT a multiplexing technique?

A. Time Division Multiplexing

B. Code Division Multiple Access
C. Frequency Division Multiplexing
D. Carrier Sense Multiple Access with Collision Detection

Slide 54: Answer 27

Correct Answer: D. Carrier Sense Multiple Access with Collision Detection

CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is not a multiplexing
technique; it is a medium access control protocol used in traditional Ethernet networks to
control how devices share the network medium and to detect collisions. The other options
(TDM, CDMA, FDM) are multiplexing methods that allow multiple signals or data streams
to share a common communication medium by dividing it by time, code, or frequency,
respectively.

Slide 55: Question 28

Which of the following is an unguided transmission medium?

A. Optical fiber
B. Twisted pair cable
C. Coaxial cable
D. Radio waves

Slide 56: Answer 28

Correct Answer: D. Radio waves

Unguided transmission media refer to wireless media where signals propagate through free
space (air or vacuum) without a physical conductor. Radio waves (including microwaves and
infrared) are examples of unguided media, used in Wi-Fi, cellular networks, satellite
communication, etc. Optical fiber, twisted pair, and coaxial cable are guided media since
they guide electromagnetic signals through a physical conduit (glass, copper wires, etc.).

Slide 57: Question 29

In an Ethernet LAN, what medium access control method is used to allow multiple
devices to share the network without speaking at the same time?

A. Token Ring passing

B. CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
C. CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance)
D. Slotted ALOHA

Slide 58: Answer 29

Correct Answer: B. CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
Classic Ethernet (IEEE 802.3 using hubs or half-duplex links) uses CSMA/CD. With
CSMA/CD, each device “listens” to the carrier (the network medium) to sense if it’s free
before transmitting. If two devices transmit simultaneously, a collision occurs; the collision is
detected and both devices stop, wait a random backoff time, then attempt to retransmit. This
method was essential for shared coaxial and hub-based Ethernet. (Wi-Fi networks use
CSMA/CA, and Token Ring networks use a token-passing protocol.)

Slide 59: Question 30

Wi-Fi networks (IEEE 802.11) use which method to handle multiple access and
minimize collisions on the wireless medium?

A. CSMA/CA (Collision Avoidance)

B. CSMA/CD (Collision Detection)
C. TDMA (Time Division Multiple Access)
D. Token passing

Slide 60: Answer 30

Correct Answer: A. CSMA/CA (Collision Avoidance)

Wi-Fi (IEEE 802.11) employs CSMA/CA – Carrier Sense Multiple Access with Collision
Avoidance. Unlike Ethernet’s collision detection, wireless devices can’t detect collisions
reliably (due to the nature of radio; a device can’t listen while transmitting). Instead, Wi-Fi
uses strategies like waiting for the medium to be clear, random backoff timers, and
acknowledgements for received frames to avoid and handle collisions. Some Wi-Fi networks
also use Request to Send/Clear to Send (RTS/CTS) handshake to further reduce collision risk
in certain scenarios.
Slide 61: Question 31

Which error detection method uses a polynomial division of the message bits, appending
the remainder to the frame?

A. Checksum
B. Cyclic Redundancy Check (CRC)
C. Parity bit
D. Hamming code

Slide 62: Answer 31

Correct Answer: B. Cyclic Redundancy Check (CRC)

The Cyclic Redundancy Check is an error-detection technique that treats the data as
coefficients of a polynomial and divides it by a generator polynomial. The remainder from
this division is appended to the frame as the CRC value (Frame Check Sequence). The
receiver performs the same division and compares remainders to detect errors. CRCs are very
effective at detecting common errors and are used in many link-layer protocols (Ethernet
frames use a 32-bit CRC). Checksum (as used in IP/TCP/UDP) is a simpler addition-based
method, parity adds a single bit, and Hamming code is for error correction.

Slide 63: Question 32

Which ARQ (Automatic Repeat reQuest) mechanism resends only the specific packets
that were lost or corrupted, rather than retransmitting everything from the error
onward?

A. Stop-and-Wait ARQ
B. Go-Back-N ARQ
C. Selective Repeat ARQ
D. Error Correction Codes (ECC)

Slide 64: Answer 32

Correct Answer: C. Selective Repeat ARQ

Selective Repeat ARQ is an error-control protocol that only retransmits the packets (frames)
that were detected as lost or erroneous, as opposed to Go-Back-N which would retransmit
that packet and all subsequent ones in the window. In Selective Repeat, the receiver can
accept and buffer out-of-order frames and will NACK (or otherwise indicate) only the
missing ones. This makes Selective Repeat more efficient in networks with higher latency or
error rates, as it avoids unnecessary retransmissions. Stop-and-Wait sends one packet at a
time (waiting for ACK each time), and ECC refers to forward error correction codes rather
than ARQ.
Slide 65: Question 33

Network congestion occurs when:

A. the total demand for network bandwidth exceeds the available capacity.
B. two nodes transmit simultaneously on a shared medium.
C. a sender transmits faster than the receiver can process.
D. packets are encrypted and cannot be processed quickly.

Slide 66: Answer 33

Correct Answer: A. The total demand for network bandwidth exceeds the available
capacity.
Congestion in a network happens when nodes (routers, switches) receive more data than they
can forward, leading to growing queues and packet delays or drops. Essentially, if too many
packets are in transit for the network to handle, performance degrades (queues overflow,
causing packet loss). Option B describes a collision (relevant in Ethernet CSMA/CD), C
refers to a flow control issue between sender/receiver, and D is unrelated (encryption
overhead could cause processing delay, but not the definition of congestion).

Slide 67: Question 34

Which device connects multiple computers in a LAN but broadcasts all incoming traffic
to all ports (i.e., it does not filter by address)?

A. Switch
B. Router
C. Hub
D. Bridge

Slide 68: Answer 34

Correct Answer: C. Hub

A hub is a simple network device operating at the Physical layer. It repeats any incoming
signal out to all other ports, so every connected device sees all traffic. Hubs do not examine
or use addresses, resulting in a shared collision domain where only one device can
successfully transmit at a time. In contrast, a switch (Layer 2) learns MAC addresses and
forwards frames only to the appropriate port, and a bridge also filters traffic by MAC address.
Routers (Layer 3) use IP addresses to route traffic between networks.

Slide 69: Question 35

Which device in a network forwards frames based on MAC addresses and thereby
reduces collision domains, typically operating at OSI Layer 2?
A. Hub
B. Switch
C. Repeater
D. Gateway

Slide 70: Answer 35

Correct Answer: B. Switch

A network switch operates at the Data Link layer (Layer 2) and forwards Ethernet frames
using MAC addresses. Each port on a switch is its own collision domain, meaning devices on
different ports do not collide with each other’s traffic. The switch builds a MAC address table
(mapping addresses to ports) and sends incoming frames only out of the port associated with
the destination MAC (or floods if unknown). This behavior contrasts with a hub (which
broadcasts to all ports). A repeater simply regenerates signals (Physical layer), and a gateway
is a broad term often referring to a device that translates between protocols (often functioning
at higher layers).

Slide 71: Question 36

What is a Virtual LAN (VLAN) used for?

A. To logically segment a LAN into separate broadcast domains without physical separation.
B. To create a secure tunnel over the Internet between two networks.
C. To extend a LAN over a metropolitan area.
D. To balance traffic load across multiple network links.

Slide 72: Answer 36

Correct Answer: A. To logically segment a LAN into separate broadcast domains

without physical separation.
A VLAN (Virtual Local Area Network) allows network administrators to partition a single
physical switch (or network) into multiple distinct networks. Devices on different VLANs
behave as if they are on different LANs altogether, even if physically connected to the same
switch. This improves security and traffic management by confining broadcast traffic to each
VLAN. Option B describes a VPN, C is a MAN, and D refers to link load balancing (like link
aggregation), none of which are the definition of a VLAN.

Slide 73: Question 37

Which of the following is used to send email from a mail client (or between mail servers)
to its destination server?

A. FTP
B. SMTP
C. IMAP
D. SNMP

Slide 74: Answer 37

Correct Answer: B. SMTP

SMTP (Simple Mail Transfer Protocol) is the protocol for sending email. An email client
uses SMTP to send outgoing mail to an SMTP server, and servers also use SMTP to relay
messages to the next hop or destination server. IMAP (and POP3) are protocols used by
clients to retrieve or read email from a mail server, FTP is for file transfer, and SNMP is for
network management. SMTP by default uses TCP port 25 for communications between
servers (and often port 587 or 465 for client submissions).

Slide 75: Question 38

Which port number is the default for HTTPS (HTTP Secure) web traffic?

A. 80
B. 443
C. 21
D. 25

Slide 76: Answer 38

Correct Answer: B. 443

HTTPS, which is HTTP layered over TLS/SSL for encryption, uses port 443 by default. This
is the standard port that web browsers connect to for secure web pages (URLs beginning with
https://). By contrast, HTTP (unsecured) uses port 80. Port 21 is used by FTP (control
channel), and port 25 is used by SMTP for email relay. So when you access a website via
HTTPS, your browser is typically communicating over TCP port 443 to exchange encrypted
HTTP data.

Slide 77: Question 39

RSA is an example of what type of cryptographic algorithm?

A. Symmetric-key encryption
B. Asymmetric (public-key) encryption
C. Hash function
D. One-time pad

Slide 78: Answer 39

Correct Answer: B. Asymmetric (public-key) encryption

RSA is a public-key (asymmetric) encryption algorithm. It uses a pair of keys: a public key
for encryption (or signature verification) and a private key for decryption (or signature
creation). This differs from symmetric-key encryption (like AES), which uses the same key
for both encryption and decryption. RSA enables things like secure key exchange and digital
signatures. Hash functions (like SHA-256) produce a fixed-size fingerprint of data (with no
key), and a one-time pad is a theoretical symmetric cipher that uses a single-use key as long
as the message.

Slide 79: Question 40

Which multiple access technique allows multiple mobile users to share the same
bandwidth by assigning unique codes to each user’s signal?

A. FDMA
B. TDMA
C. CDMA
D. SDMA

Slide 80: Answer 40

Correct Answer: C. CDMA

CDMA (Code Division Multiple Access) allows multiple users to occupy the same time and
frequency spectrum simultaneously by encoding each user’s signal with a unique
pseudonoise code. The signals appear overlapped but can be separated at the receiver by
correlating with the unique code for each sender. FDMA (Frequency Division) separates
users by different frequency channels, TDMA separates them by time slots, and SDMA
(Space Division) could refer to separating by physical space or antennas. CDMA was notably
used in certain 2G/3G mobile networks (e.g., IS-95, CDMA2000).

Slide 81: Question 41

Which layer of the TCP/IP model handles establishing a connection-oriented session via
a three-way handshake before data transmission?

A. Application layer
B. Transport layer
C. Internet layer
D. Link layer

Slide 82: Answer 41

Correct Answer: B. Transport layer

The Transport layer in TCP/IP (which includes protocols like TCP and UDP) is responsible
for end-to-end communication between hosts. TCP, in particular, establishes a connection-
oriented session using the three-way handshake (SYN, SYN-ACK, ACK) to set up
synchronization and initial sequence numbers before any actual data is sent. This handshake
ensures both sides are ready and paves the way for reliable delivery. UDP, also at the
transport layer, does not establish connections (no handshake). The Internet layer (network
layer) handles routing (IP), and Application layer protocols ride on the transport connection
that TCP provides.

Slide 83: Question 42

What is the purpose of the TCP three-way handshake (SYN, SYN-ACK, ACK)?

A. To establish a reliable connection between client and server before data transfer.
B. To probe the network for the fastest route.
C. To exchange encryption keys for a secure session.
D. To terminate a TCP connection gracefully.

Slide 84: Answer 42

Correct Answer: A. To establish a reliable connection between client and server before
data transfer.
The TCP three-way handshake establishes a connection-oriented session and synchronizes
sequence numbers between the two communicating hosts. In the handshake, the client sends a
SYN packet, the server responds with SYN-ACK, and then the client replies with an ACK.
This process ensures that both sides agree on initial sequence numbers and are ready to
transmit data, thereby setting up a reliable connection. (Encryption key exchange is not
inherently part of TCP; it would be handled by protocols like TLS on top of TCP. Connection
termination uses a different FIN/ACK handshake sequence.)

Slide 85: Question 43

Which protocol is used by the ping utility to test network connectivity between two
hosts?

A. DNS
B. ICMP
C. ARP
D. SMTP

Slide 86: Answer 43

Correct Answer: B. ICMP

Ping uses ICMP (Internet Control Message Protocol), specifically ICMP Echo Request and
Echo Reply messages, to test reachability between hosts. When you ping an IP address, your
computer sends an ICMP Echo Request; the destination, if reachable and configured to
respond, replies with an ICMP Echo Reply. Ping measures the round-trip time and packet
loss. DNS translates names to IPs, ARP resolves IP to MAC on local networks, and SMTP is
for email—none of which are used by ping.
Slide 87: Question 44

Which OSI layer is responsible for data encryption, compression, and translation of
data formats (ensuring that data from the application layer of one system can be read
by the application layer of another)?

A. Session layer
B. Presentation layer
C. Network layer
D. Application layer

Slide 88: Answer 44

Correct Answer: B. Presentation layer

The Presentation layer (Layer 6 of OSI) acts as the translator between the application and the
network. It handles format translation (e.g., character encoding, data serialization), data
compression, and encryption/decryption when required. Essentially, it ensures that the data
sent by the application layer of one system is understandable by the application layer of
another, despite differences in data representation. Encryption can occur at various layers, but
the OSI model conceptually places it in the Presentation layer. The Session layer (Layer 5)
manages dialogs, and the Application layer (Layer 7) interfaces with software applications.

Slide 89: Question 45

Which protocol automates the assignment of IP addresses (along with subnet masks and
gateways) to hosts in a network?

A. DNS
B. ARP
C. DHCP
D. ICMP

Slide 90: Answer 45

Correct Answer: C. DHCP

DHCP (Dynamic Host Configuration Protocol) automatically assigns IP configuration to
clients. When a device connects to a network, it can request an IP address from a DHCP
server, which leases an IP address, subnet mask, default gateway, DNS server info, etc., to
the client for a certain period. This saves administrators from manually configuring these
settings on each device. DNS translates domain names to IPs, ARP resolves IP to MAC on
local link, and ICMP is used for control messages like ping – none of those assign IPs.

Slide 91: Question 46

What is the default subnet mask for an IPv4 Class C network address?

A. 255.0.0.0
B. 255.255.0.0
C. 255.255.255.0
D. 255.255.255.255

Slide 92: Answer 46

Correct Answer: C. 255.255.255.0

Class C IPv4 addresses (in the historical classful addressing scheme) have a default subnet
mask of 255.255.255.0 (/24 in CIDR notation). This mask means the first three octets (24
bits) represent the network portion and the last octet (8 bits) represents the host portion. For
example, in a Class C network like 192.168.5.0, the default mask 255.255.255.0 yields a
network address of 192.168.5.0 and allows host addresses from 192.168.5.1 up to
192.168.5.254.

Slide 93: Question 47

Which layer of the OSI model manages dialogue control and synchronizes interaction
between two communicating applications (for example, by establishing checkpoints in a
data stream)?

A. Transport layer
B. Session layer
C. Presentation layer
D. Data Link layer

Slide 94: Answer 47

Correct Answer: B. Session layer

The Session layer (Layer 5 of OSI) is responsible for controlling the conversations (sessions)
between applications. It establishes, manages, and terminates sessions between two
communicating hosts. This layer can set synchronization points (checkpoints) in data streams
for recovery in case of failures and manage dialogue (for instance, who transmits when in
half-duplex situations). While not as commonly referenced in modern Internet protocols
(where its functions are often handled by lower layers or the application itself), it
conceptually provides structured, managed communication sessions beyond simple transport
of data.

Slide 95: Question 48

An IPv4 address consists of how many bits?

A. 4 bits
B. 32 bits
C. 64 bits
D. 128 bits

Slide 96: Answer 48

Correct Answer: B. 32 bits

IPv4 addresses are 32 bits in length. They are typically expressed in dotted-decimal notation
as four octets (for example, 192.0.2.5), where each octet represents 8 bits of the address. This
32-bit size yields about 4.3 billion possible addresses (though practical usable addresses are
fewer due to reservations and network structuring). IPv6 addresses, in comparison, are 128
bits.

Slide 97: Question 49

Which term describes the unique identifier assigned to a process or service on a host,
used by the Transport layer to direct data to the correct application?

A. MAC address
B. IP address
C. Port number
D. URL

Slide 98: Answer 49

Correct Answer: C. Port number

A port number identifies a specific process or service on a host in TCP/IP networking. The
Transport layer (TCP/UDP) uses port numbers to distinguish between multiple running
services or applications on a single device. For example, HTTP typically uses port 80, and
HTTPS uses port 443. An IP address combined with a port number forms a socket address
that uniquely identifies a network connection endpoint. MAC addresses operate at the link
layer, IP addresses identify hosts/networks at the network layer, and URLs are user-friendly
resource identifiers used at the application layer.

Slide 99: Question 50

The TCP/IP protocol suite was developed ____ the OSI model was created.

A. before
B. after
C. at the same time as
D. independently with no relation to

Slide 100: Answer 50

Correct Answer: A. before
The TCP/IP model (and protocols) were developed prior to the OSI reference model. Early
research and implementation of TCP/IP began in the 1970s (with TCP/IP protocols being
adopted by ARPANET in the early 1980s), whereas the OSI model was published in 1984.
The OSI model was a theoretical framework to standardize network functions, while TCP/IP
evolved from practical experiments. Although TCP/IP was developed independently of OSI,
it can be roughly mapped to the OSI layers for comparison.