CS 3251 Computer Networking I Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf.
1. In the context of computer networking, which statement most
accurately describes the primary purpose of a computer network?
A. To increase the processing speed of individual computers
B. To allow interconnected devices to exchange data and share
resources using communication protocols
C. To replace operating systems with distributed hardware
D. To eliminate the need for application software
Answer: B. To allow interconnected devices to exchange data and share
resources using communication protocols
Rationale: A computer network connects devices so that they can
communicate, exchange information, and share resources such as files,
services, storage, and Internet connectivity.
2. Which layer of the OSI reference model is primarily responsible for
providing end-to-end communication, including segmentation, flow
control, and reliability?
A. Network layer
B. Data Link layer
C. Transport layer
D. Session layer
,Answer: C. Transport layer
Rationale: The Transport layer provides end-to-end delivery services
between applications, including segmentation, reliability mechanisms,
flow control, and multiplexing through mechanisms such as TCP.
3. Which protocol is primarily responsible for translating a human-
readable domain name such as www.example.com into an IP address?
A. DHCP
B. DNS
C. FTP
D. ARP
Answer: B. DNS
Rationale: The Domain Name System (DNS) maps domain names to IP
addresses and other resource records, allowing users and applications to
identify network hosts using meaningful names.
4. Which of the following best describes packet switching?
A. A dedicated physical path is permanently reserved between
communicating devices
B. Data is transmitted as a continuous electrical signal without
addressing
C. Data is divided into packets that are independently forwarded
through a network
D. Each application requires a separate physical cable between
communicating hosts
Answer: C. Data is divided into packets that are independently forwarded
through a network
Rationale: Packet-switched networks divide data into packets, which
contain addressing and control information and may traverse shared
network resources through different paths.
, 5. Which device normally operates at the Network layer of the OSI model
and makes forwarding decisions primarily using IP addresses?
A. Hub
B. Switch
C. Router
D. Repeater
Answer: C. Router
Rationale: Routers operate primarily at Layer 3 and use network-layer
addressing and routing information to determine where IP packets should
be forwarded.
6. Which protocol is connection-oriented and provides reliable, ordered
delivery of a byte stream between applications?
A. UDP
B. IP
C. TCP
D. ARP
Answer: C. TCP
Rationale: TCP establishes a logical connection between endpoints and
uses sequencing, acknowledgments, retransmission, and flow and
congestion control to provide reliable ordered delivery.
7. Which characteristic most accurately distinguishes UDP from TCP?
A. UDP requires a three-way handshake before data transmission
B. UDP provides reliable retransmission of lost segments
C. UDP is connectionless and does not inherently guarantee reliable or
ordered delivery
D. UDP cannot be used by application-layer protocols
Answer: C. UDP is connectionless and does not inherently guarantee
reliable or ordered delivery
, Rationale: UDP provides a lightweight datagram service without TCP's
connection establishment, retransmission, sequencing, and congestion-
control mechanisms.
8. A communication link has a transmission rate of 10 Mbps.
Approximately how long does it take to transmit a 5-megabit file,
ignoring propagation, processing, and queuing delays?
A. 0.05 seconds
B. 0.5 seconds
C. 5 seconds
D. 50 seconds
Answer: B. 0.5 seconds
Rationale: Transmission time is calculated as data size divided by
transmission rate, so 5 Mb ÷ 10 Mb/s = 0.5 seconds.
9. Which type of delay represents the time required to push all the bits
of a packet onto a communication link?
A. Propagation delay
B. Processing delay
C. Transmission delay
D. Queuing delay
Answer: C. Transmission delay
Rationale: Transmission delay depends on packet length and link
transmission rate and is calculated as L/R, where L is the packet size in bits
and R is the link rate in bits per second.
10. Which type of delay is determined primarily by the physical
distance between sender and receiver and the propagation speed of
the medium?
A. Transmission delay
B. Propagation delay
C. Processing delay
D. Queuing delay
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf.
1. In the context of computer networking, which statement most
accurately describes the primary purpose of a computer network?
A. To increase the processing speed of individual computers
B. To allow interconnected devices to exchange data and share
resources using communication protocols
C. To replace operating systems with distributed hardware
D. To eliminate the need for application software
Answer: B. To allow interconnected devices to exchange data and share
resources using communication protocols
Rationale: A computer network connects devices so that they can
communicate, exchange information, and share resources such as files,
services, storage, and Internet connectivity.
2. Which layer of the OSI reference model is primarily responsible for
providing end-to-end communication, including segmentation, flow
control, and reliability?
A. Network layer
B. Data Link layer
C. Transport layer
D. Session layer
,Answer: C. Transport layer
Rationale: The Transport layer provides end-to-end delivery services
between applications, including segmentation, reliability mechanisms,
flow control, and multiplexing through mechanisms such as TCP.
3. Which protocol is primarily responsible for translating a human-
readable domain name such as www.example.com into an IP address?
A. DHCP
B. DNS
C. FTP
D. ARP
Answer: B. DNS
Rationale: The Domain Name System (DNS) maps domain names to IP
addresses and other resource records, allowing users and applications to
identify network hosts using meaningful names.
4. Which of the following best describes packet switching?
A. A dedicated physical path is permanently reserved between
communicating devices
B. Data is transmitted as a continuous electrical signal without
addressing
C. Data is divided into packets that are independently forwarded
through a network
D. Each application requires a separate physical cable between
communicating hosts
Answer: C. Data is divided into packets that are independently forwarded
through a network
Rationale: Packet-switched networks divide data into packets, which
contain addressing and control information and may traverse shared
network resources through different paths.
, 5. Which device normally operates at the Network layer of the OSI model
and makes forwarding decisions primarily using IP addresses?
A. Hub
B. Switch
C. Router
D. Repeater
Answer: C. Router
Rationale: Routers operate primarily at Layer 3 and use network-layer
addressing and routing information to determine where IP packets should
be forwarded.
6. Which protocol is connection-oriented and provides reliable, ordered
delivery of a byte stream between applications?
A. UDP
B. IP
C. TCP
D. ARP
Answer: C. TCP
Rationale: TCP establishes a logical connection between endpoints and
uses sequencing, acknowledgments, retransmission, and flow and
congestion control to provide reliable ordered delivery.
7. Which characteristic most accurately distinguishes UDP from TCP?
A. UDP requires a three-way handshake before data transmission
B. UDP provides reliable retransmission of lost segments
C. UDP is connectionless and does not inherently guarantee reliable or
ordered delivery
D. UDP cannot be used by application-layer protocols
Answer: C. UDP is connectionless and does not inherently guarantee
reliable or ordered delivery
, Rationale: UDP provides a lightweight datagram service without TCP's
connection establishment, retransmission, sequencing, and congestion-
control mechanisms.
8. A communication link has a transmission rate of 10 Mbps.
Approximately how long does it take to transmit a 5-megabit file,
ignoring propagation, processing, and queuing delays?
A. 0.05 seconds
B. 0.5 seconds
C. 5 seconds
D. 50 seconds
Answer: B. 0.5 seconds
Rationale: Transmission time is calculated as data size divided by
transmission rate, so 5 Mb ÷ 10 Mb/s = 0.5 seconds.
9. Which type of delay represents the time required to push all the bits
of a packet onto a communication link?
A. Propagation delay
B. Processing delay
C. Transmission delay
D. Queuing delay
Answer: C. Transmission delay
Rationale: Transmission delay depends on packet length and link
transmission rate and is calculated as L/R, where L is the packet size in bits
and R is the link rate in bits per second.
10. Which type of delay is determined primarily by the physical
distance between sender and receiver and the propagation speed of
the medium?
A. Transmission delay
B. Propagation delay
C. Processing delay
D. Queuing delay
