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COMPUTER NETWORKING: A TOP-DOWN APPROACH, 9TH
EDITION EXAM GUIDE AND CORRECT ANSWERS LATEST EDITION
2026
Computer Networking: A Top-Down Approach, 9th Edition — 250 MCQs with Rationales
Summarized 8-Point Exam Coverage
This question bank is aligned with Computer Networking: A Top-Down Approach (9th Edition) by
James F. Kurose and Keith W. Ross. The textbook follows a top-down pedagogy, beginning at the
application layer and proceeding downward to the physical layer. The 9th Edition adds coverage
of HTTP/3 and QUIC, Wi-Fi 6, 5G cellular networks, software-defined networking, and updated
network security material.
The eight chapters and their approximate question distributions are:
1. Computer Networks and the Internet (Questions 1–35) — Network edge, network core,
packet switching, circuit switching, delay, loss, throughput, protocol layers,
encapsulation, and network security overview.
2. Application Layer (Questions 36–75) — Network application architectures, HTTP/1.1,
HTTP/2, HTTP/3 and QUIC, SMTP, DNS, video streaming, CDNs, and socket programming.
3. Transport Layer (Questions 76–115) — Multiplexing and demultiplexing, UDP, reliable
data transfer, Go-Back-N, Selective Repeat, TCP, flow control, congestion control, and
ECN.
4. The Network Layer: Data Plane (Questions 116–150) — Router architecture, IPv4, IPv6,
addressing, NAT, generalized forwarding, SDN, OpenFlow, and middleboxes.
5. The Network Layer: Control Plane (Questions 151–180) — Link-state and distance-
vector routing, OSPF, BGP, SDN controllers, ICMP, SNMP, and NETCONF/YANG.
6. The Link Layer and LANs (Questions 181–215) — Error detection, multiple access
protocols, ARP, Ethernet, switches, VLANs, MPLS, VXLANs, and data center networking.
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7. Wireless and Mobile Networks (Questions 216–235) — Wireless channel characteristics,
Wi-Fi (802.11), 5G radio access and core networks, mobility principles, Bluetooth,
satellite, and IoT.
8. Security in Computer Networks (Questions 236–250) — Symmetric and public-key
cryptography, message integrity, digital signatures, TLS, IPsec, VPNs, firewalls, and
intrusion detection.
Each question stem is at least 15 words in length, and every question includes a detailed
rationale explaining both the correct answer and why the distractors are incorrect.
CHAPTER 1: COMPUTER NETWORKS AND THE INTERNET (Questions 1–35)
1. Which of the following best describes the term "protocol" as it is used in the context of
computer networking?
A) A physical device that connects two or more networks together
B) A set of rules that governs the format and order of messages exchanged between
communicating entities
C) A software application that allows users to browse the World Wide Web
D) A type of cable used to transmit data between computers
Correct Answer: B
Rationale: A protocol defines the format and order of messages exchanged between two or
more communicating entities, as well as the actions taken on the transmission and/or receipt of
a message or other event. Physical devices, web browsers, and cables are not protocols.
2. Which of the following is an example of an end system (host) in the Internet architecture?
A) A router located in the network core
B) A desktop computer, smartphone, or web server
C) A switch inside a local area network
D) A fiber-optic cable connecting two cities
Correct Answer: B
Rationale: End systems (hosts) are devices such as desktop computers, smartphones, and web
servers that sit at the edge of the Internet. Routers, switches, and cables are part of the
network core or physical infrastructure.
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3. A user is streaming a high-definition video and notices that the video occasionally pauses
to buffer. Which performance metric is most directly related to this buffering behavior?
A) Packet loss
B) Throughput
C) Delay jitter
D) Bandwidth
Correct Answer: B
Rationale: Throughput is the rate at which bits are transferred between sender and receiver. If
throughput is insufficient for the video's bitrate, buffering occurs. Delay jitter and packet loss
can also affect streaming quality, but buffering is most directly related to throughput.
4. Which of the following accurately describes the difference between packet switching and
circuit switching?
A) Packet switching reserves dedicated resources for the duration of a communication session.
B) Circuit switching divides messages into packets that are transmitted independently.
C) Packet switching allows resources to be shared among many users, while circuit switching
reserves resources for the duration of a session.
D) Circuit switching is always faster than packet switching for all types of traffic.
Correct Answer: C
Rationale: Packet switching allows multiple users to share network resources on demand,
whereas circuit switching reserves dedicated resources (e.g., a circuit) for the entire duration of
a communication session. Packet switching does not reserve resources, and circuit switching
does not divide messages into packets.
5. Which type of access network technology uses the existing telephone infrastructure to
provide high-speed Internet access?
A) Cable modem
B) DSL (Digital Subscriber Line)
C) Fiber to the Home (FTTH)
D) Satellite
Correct Answer: B
Rationale: DSL uses the existing telephone infrastructure (twisted-pair copper wire) to provide
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high-speed Internet access. Cable modems use cable TV infrastructure, FTTH uses fiber-optic
cable, and satellite uses wireless transmission.
6. Which physical medium is immune to electromagnetic interference and is commonly used
for long-haul, high-bandwidth backbone links?
A) Twisted-pair copper wire
B) Coaxial cable
C) Fiber-optic cable
D) Radio spectrum
Correct Answer: C
Rationale: Fiber-optic cable is immune to electromagnetic interference, has very low
attenuation, and is commonly used for long-haul, high-bandwidth backbone links. Twisted-pair
and coaxial cables are susceptible to interference, and radio spectrum is subject to interference
and regulation.
7. In a packet-switched network, what is the primary cause of queuing delay at a router?
A) The router's processing speed exceeding the link transmission rate
B) Packets arriving at a rate that temporarily exceeds the link's transmission capacity
C) The physical length of the link between routers
D) The number of protocols implemented on the router
Correct Answer: B
Rationale: Queuing delay occurs when packets arrive at a router's output link faster than the
link can transmit them. If the arrival rate temporarily exceeds the transmission rate, packets
must wait in a queue. Processing speed and link length affect other types of delay.
8. Which of the following is the correct order of protocol layers in the Internet protocol stack,
from top to bottom?
A) Physical, Link, Network, Transport, Application
B) Application, Transport, Network, Link, Physical
C) Application, Network, Transport, Link, Physical
D) Transport, Application, Network, Link, Physical
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COMPUTER NETWORKING: A TOP-DOWN APPROACH, 9TH
EDITION EXAM GUIDE AND CORRECT ANSWERS LATEST EDITION
2026
Computer Networking: A Top-Down Approach, 9th Edition — 250 MCQs with Rationales
Summarized 8-Point Exam Coverage
This question bank is aligned with Computer Networking: A Top-Down Approach (9th Edition) by
James F. Kurose and Keith W. Ross. The textbook follows a top-down pedagogy, beginning at the
application layer and proceeding downward to the physical layer. The 9th Edition adds coverage
of HTTP/3 and QUIC, Wi-Fi 6, 5G cellular networks, software-defined networking, and updated
network security material.
The eight chapters and their approximate question distributions are:
1. Computer Networks and the Internet (Questions 1–35) — Network edge, network core,
packet switching, circuit switching, delay, loss, throughput, protocol layers,
encapsulation, and network security overview.
2. Application Layer (Questions 36–75) — Network application architectures, HTTP/1.1,
HTTP/2, HTTP/3 and QUIC, SMTP, DNS, video streaming, CDNs, and socket programming.
3. Transport Layer (Questions 76–115) — Multiplexing and demultiplexing, UDP, reliable
data transfer, Go-Back-N, Selective Repeat, TCP, flow control, congestion control, and
ECN.
4. The Network Layer: Data Plane (Questions 116–150) — Router architecture, IPv4, IPv6,
addressing, NAT, generalized forwarding, SDN, OpenFlow, and middleboxes.
5. The Network Layer: Control Plane (Questions 151–180) — Link-state and distance-
vector routing, OSPF, BGP, SDN controllers, ICMP, SNMP, and NETCONF/YANG.
6. The Link Layer and LANs (Questions 181–215) — Error detection, multiple access
protocols, ARP, Ethernet, switches, VLANs, MPLS, VXLANs, and data center networking.
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7. Wireless and Mobile Networks (Questions 216–235) — Wireless channel characteristics,
Wi-Fi (802.11), 5G radio access and core networks, mobility principles, Bluetooth,
satellite, and IoT.
8. Security in Computer Networks (Questions 236–250) — Symmetric and public-key
cryptography, message integrity, digital signatures, TLS, IPsec, VPNs, firewalls, and
intrusion detection.
Each question stem is at least 15 words in length, and every question includes a detailed
rationale explaining both the correct answer and why the distractors are incorrect.
CHAPTER 1: COMPUTER NETWORKS AND THE INTERNET (Questions 1–35)
1. Which of the following best describes the term "protocol" as it is used in the context of
computer networking?
A) A physical device that connects two or more networks together
B) A set of rules that governs the format and order of messages exchanged between
communicating entities
C) A software application that allows users to browse the World Wide Web
D) A type of cable used to transmit data between computers
Correct Answer: B
Rationale: A protocol defines the format and order of messages exchanged between two or
more communicating entities, as well as the actions taken on the transmission and/or receipt of
a message or other event. Physical devices, web browsers, and cables are not protocols.
2. Which of the following is an example of an end system (host) in the Internet architecture?
A) A router located in the network core
B) A desktop computer, smartphone, or web server
C) A switch inside a local area network
D) A fiber-optic cable connecting two cities
Correct Answer: B
Rationale: End systems (hosts) are devices such as desktop computers, smartphones, and web
servers that sit at the edge of the Internet. Routers, switches, and cables are part of the
network core or physical infrastructure.
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,Page 3 of 79
3. A user is streaming a high-definition video and notices that the video occasionally pauses
to buffer. Which performance metric is most directly related to this buffering behavior?
A) Packet loss
B) Throughput
C) Delay jitter
D) Bandwidth
Correct Answer: B
Rationale: Throughput is the rate at which bits are transferred between sender and receiver. If
throughput is insufficient for the video's bitrate, buffering occurs. Delay jitter and packet loss
can also affect streaming quality, but buffering is most directly related to throughput.
4. Which of the following accurately describes the difference between packet switching and
circuit switching?
A) Packet switching reserves dedicated resources for the duration of a communication session.
B) Circuit switching divides messages into packets that are transmitted independently.
C) Packet switching allows resources to be shared among many users, while circuit switching
reserves resources for the duration of a session.
D) Circuit switching is always faster than packet switching for all types of traffic.
Correct Answer: C
Rationale: Packet switching allows multiple users to share network resources on demand,
whereas circuit switching reserves dedicated resources (e.g., a circuit) for the entire duration of
a communication session. Packet switching does not reserve resources, and circuit switching
does not divide messages into packets.
5. Which type of access network technology uses the existing telephone infrastructure to
provide high-speed Internet access?
A) Cable modem
B) DSL (Digital Subscriber Line)
C) Fiber to the Home (FTTH)
D) Satellite
Correct Answer: B
Rationale: DSL uses the existing telephone infrastructure (twisted-pair copper wire) to provide
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high-speed Internet access. Cable modems use cable TV infrastructure, FTTH uses fiber-optic
cable, and satellite uses wireless transmission.
6. Which physical medium is immune to electromagnetic interference and is commonly used
for long-haul, high-bandwidth backbone links?
A) Twisted-pair copper wire
B) Coaxial cable
C) Fiber-optic cable
D) Radio spectrum
Correct Answer: C
Rationale: Fiber-optic cable is immune to electromagnetic interference, has very low
attenuation, and is commonly used for long-haul, high-bandwidth backbone links. Twisted-pair
and coaxial cables are susceptible to interference, and radio spectrum is subject to interference
and regulation.
7. In a packet-switched network, what is the primary cause of queuing delay at a router?
A) The router's processing speed exceeding the link transmission rate
B) Packets arriving at a rate that temporarily exceeds the link's transmission capacity
C) The physical length of the link between routers
D) The number of protocols implemented on the router
Correct Answer: B
Rationale: Queuing delay occurs when packets arrive at a router's output link faster than the
link can transmit them. If the arrival rate temporarily exceeds the transmission rate, packets
must wait in a queue. Processing speed and link length affect other types of delay.
8. Which of the following is the correct order of protocol layers in the Internet protocol stack,
from top to bottom?
A) Physical, Link, Network, Transport, Application
B) Application, Transport, Network, Link, Physical
C) Application, Network, Transport, Link, Physical
D) Transport, Application, Network, Link, Physical
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