AT&T TKT II (Latest 2026/2027 Update)
Complete Questions and Guide Answers,
100% Verified Graded A+
1. What does the acronym OSI stand for in networking?
A. Open Systems Interconnection
B. Open Source Integration
C. Operational Systems Interface
D. Optical Signal Interconnection
Correct Answer: A
Rationale: OSI stands for Open Systems Interconnection. The OSI model is a conceptual
framework that standardizes the functions of a telecommunication or computing system
into seven abstraction layers.
2. Which layer of the OSI model is responsible for routing and forwarding data
packets?
A. Physical Layer
B. Data Link Layer
C. Network Layer
D. Transport Layer
Correct Answer: C
Rationale: The Network Layer (Layer 3) is responsible for packet forwarding, routing,
and addressing. It determines the best path for data to travel from source to destination.
3. What is the primary function of the Transport Layer in the OSI model?
A. Error detection and correction
B. End-to-end communication and data flow control
C. Physical addressing
D. Signal modulation
,Correct Answer: B
Rationale: The Transport Layer (Layer 4) is responsible for end-to-end communication,
data flow control, error recovery, and segmentation/reassembly of data.
4. Which of the following is a connectionless transport layer protocol?
A. TCP
B. UDP
C. IP
D. ICMP
Correct Answer: B
Rationale: UDP (User Datagram Protocol) is a connectionless transport layer protocol. It
does not establish a connection before sending data and does not guarantee delivery.
5. What is the purpose of the Address Resolution Protocol (ARP)?
A. To resolve IP addresses to MAC addresses
B. To resolve MAC addresses to IP addresses
C. To assign IP addresses dynamically
D. To route packets between networks
Correct Answer: A
Rationale: ARP resolves IP addresses to MAC addresses. It is used to find the physical
(MAC) address of a device on a local network given its IP address.
6. What is the maximum transmission unit (MTU) for Ethernet frames?
A. 1,500 bytes
B. 1,518 bytes
C. 9,000 bytes
D. 64 bytes
Correct Answer: A
Rationale: The standard MTU for Ethernet is 1,500 bytes. Jumbo frames can be up to
9,000 bytes but are not standard for all networks.
7. What is the difference between a router and a switch?
A. Routers operate at Layer 2; switches operate at Layer 3
B. Routers operate at Layer 3; switches operate at Layer 2
, C. Routers and switches both operate at Layer 2
D. Routers and switches both operate at Layer 3
Correct Answer: B
Rationale: Routers operate at Layer 3 (Network Layer) and route packets between
different networks. Switches operate at Layer 2 (Data Link Layer) and forward frames
within the same network.
8. Which protocol is used to dynamically assign IP addresses to devices on a
network?
A. DNS
B. DHCP
C. ARP
D. ICMP
Correct Answer: B
Rationale: DHCP (Dynamic Host Configuration Protocol) automatically assigns IP
addresses and other network configuration parameters to devices on a network.
9. What is the loopback IP address?
A. 0.0.0.0
B. 127.0.0.1
C. 192.168.1.1
D. 255.255.255.255
Correct Answer: B
Rationale: The loopback address 127.0.0.1 (localhost) is used to test network
connectivity on the local machine without sending traffic to the network.
10. What is the purpose of a subnet mask?
A. To identify the network portion of an IP address
B. To identify the host portion of an IP address
C. To encrypt network traffic
D. To assign MAC addresses
Complete Questions and Guide Answers,
100% Verified Graded A+
1. What does the acronym OSI stand for in networking?
A. Open Systems Interconnection
B. Open Source Integration
C. Operational Systems Interface
D. Optical Signal Interconnection
Correct Answer: A
Rationale: OSI stands for Open Systems Interconnection. The OSI model is a conceptual
framework that standardizes the functions of a telecommunication or computing system
into seven abstraction layers.
2. Which layer of the OSI model is responsible for routing and forwarding data
packets?
A. Physical Layer
B. Data Link Layer
C. Network Layer
D. Transport Layer
Correct Answer: C
Rationale: The Network Layer (Layer 3) is responsible for packet forwarding, routing,
and addressing. It determines the best path for data to travel from source to destination.
3. What is the primary function of the Transport Layer in the OSI model?
A. Error detection and correction
B. End-to-end communication and data flow control
C. Physical addressing
D. Signal modulation
,Correct Answer: B
Rationale: The Transport Layer (Layer 4) is responsible for end-to-end communication,
data flow control, error recovery, and segmentation/reassembly of data.
4. Which of the following is a connectionless transport layer protocol?
A. TCP
B. UDP
C. IP
D. ICMP
Correct Answer: B
Rationale: UDP (User Datagram Protocol) is a connectionless transport layer protocol. It
does not establish a connection before sending data and does not guarantee delivery.
5. What is the purpose of the Address Resolution Protocol (ARP)?
A. To resolve IP addresses to MAC addresses
B. To resolve MAC addresses to IP addresses
C. To assign IP addresses dynamically
D. To route packets between networks
Correct Answer: A
Rationale: ARP resolves IP addresses to MAC addresses. It is used to find the physical
(MAC) address of a device on a local network given its IP address.
6. What is the maximum transmission unit (MTU) for Ethernet frames?
A. 1,500 bytes
B. 1,518 bytes
C. 9,000 bytes
D. 64 bytes
Correct Answer: A
Rationale: The standard MTU for Ethernet is 1,500 bytes. Jumbo frames can be up to
9,000 bytes but are not standard for all networks.
7. What is the difference between a router and a switch?
A. Routers operate at Layer 2; switches operate at Layer 3
B. Routers operate at Layer 3; switches operate at Layer 2
, C. Routers and switches both operate at Layer 2
D. Routers and switches both operate at Layer 3
Correct Answer: B
Rationale: Routers operate at Layer 3 (Network Layer) and route packets between
different networks. Switches operate at Layer 2 (Data Link Layer) and forward frames
within the same network.
8. Which protocol is used to dynamically assign IP addresses to devices on a
network?
A. DNS
B. DHCP
C. ARP
D. ICMP
Correct Answer: B
Rationale: DHCP (Dynamic Host Configuration Protocol) automatically assigns IP
addresses and other network configuration parameters to devices on a network.
9. What is the loopback IP address?
A. 0.0.0.0
B. 127.0.0.1
C. 192.168.1.1
D. 255.255.255.255
Correct Answer: B
Rationale: The loopback address 127.0.0.1 (localhost) is used to test network
connectivity on the local machine without sending traffic to the network.
10. What is the purpose of a subnet mask?
A. To identify the network portion of an IP address
B. To identify the host portion of an IP address
C. To encrypt network traffic
D. To assign MAC addresses
