Which of the following statements about the OSI model is correct?

The correct answer is C: Each layer provides services to the layer above it. The OSI model is designed such that each layer provides services to the layer above it, following a hierarchical structure.

A packet arrives at a router with a damaged frame header. At which OSI layer should this be detected?

The correct answer is B: Data Link Layer. The Data Link Layer (Layer 2) uses CRC (Cyclic Redundancy Check) to detect frame errors and corruption in the frame header.

In a complex network troubleshooting scenario, packets are being dropped at high rates despite connectivity. Which combination of layers should be investigated?

The correct answer is B: Layers 2, 3, and 4. Packet drops can occur due to congestion (Layer 4), routing issues (Layer 3), or hardware problems (Layer 2). Investigation should span these layers.

A network experiences frame corruption on a specific link. Which OSI layer mechanism would detect this error, and what would typically happen to the corrupted frame?

The correct answer is B: Layer 2 detects it using CRC; the frame is typically discarded. The Data Link Layer (Layer 2) uses CRC (Cyclic Redundancy Check) to detect frame corruption. Corrupted frames are discarded; higher layers handle retransmission if necessary.

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Networking

OSI, TCP/IP, protocols, routing, security

29 Q 1 Topics Take Mock Test

Difficulty: All Easy Medium Hard 11–20 of 29

Topics in Networking

All OSI Model 100

Q.11 Hard OSI Model

When implementing network monitoring with packet sniffing at multiple layers, which combination accurately represents the data structures captured at each layer?

A Layer 2: Frames; Layer 3: Packets; Layer 4: Segments/Datagrams

B Layer 1: Bits; Layer 2: Packets; Layer 3: Frames

C Layer 3: Datagrams; Layer 4: Packets; Layer 5: Messages

D Layer 2: Segments; Layer 3: Frames; Layer 4: Packets

Correct Answer: A. Layer 2: Frames; Layer 3: Packets; Layer 4: Segments/Datagrams

EXPLANATION

Layer 2 creates Frames with MAC addresses, Layer 3 creates Packets with IP addresses, and Layer 4 creates Segments (TCP) or Datagrams (UDP).

Test

Q.12 Hard OSI Model

A network architect must design a system where two applications on the same computer communicate without leaving the system. Which OSI layers are bypassed in this internal communication?

A Layers 1 and 2

B Layers 2 and 3

C Layers 1, 2, and 3

D No layers are bypassed; all are used

Correct Answer: C. Layers 1, 2, and 3

EXPLANATION

Internal inter-process communication (IPC) bypasses physical transmission and network routing, skipping Layers 1-3, and operates at Layers 4-7.

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Q.13 Hard OSI Model

In a load-balancing scenario, traffic is distributed across multiple servers based on source IP addresses. At which OSI layer does this decision-making primarily occur?

A Data Link Layer

B Network Layer

C Transport Layer

D Application Layer

Correct Answer: B. Network Layer

EXPLANATION

Load balancing based on IP addresses operates at the Network Layer (Layer 3) for Layer 3 load balancing, though advanced load balancers work at higher layers.

Test

Q.14 Hard OSI Model

Consider a scenario where SSL/TLS encryption is implemented. At which OSI layer is the encryption applied, and through which layer does encrypted traffic pass without modification?

A Layer 4; Layers 1-3

B Layer 6; Layers 1-5

C Layer 7; Layers 1-6

D Layers 4-6; Layer 7 only

Correct Answer: C. Layer 7; Layers 1-6

EXPLANATION

SSL/TLS operates at Layer 7 (Application Layer), encrypting application data. Lower layers (1-6) transparently carry encrypted data without understanding its content.

Test

Q.15 Hard OSI Model

An organization implements network segmentation using VLANs. At which OSI layer does VLAN tagging primarily operate, and which layer processes these tags?

A Layer 4; Layer 3

B Layer 2; Layer 2

C Layer 3; Layer 4

D Layer 1; Layer 2

Correct Answer: B. Layer 2; Layer 2

EXPLANATION

VLAN tagging operates at Layer 2 (Data Link Layer) using 802.1Q tags, and switches process these tags at Layer 2 to isolate traffic.

Test

Q.16 Hard OSI Model

A network protocol analyzer shows that frames are arriving at a computer but being dropped at the Network Layer. What is the most likely cause?

A Physical cable disconnection

B Incorrect IP address or routing table entry

C MAC address table overflow

D Application software crash

Correct Answer: B. Incorrect IP address or routing table entry

EXPLANATION

If frames arrive at Layer 2 but are dropped at Layer 3, the issue involves IP addressing, routing tables, or network configuration at the Network Layer.

Test

Q.17 Hard OSI Model

In analyzing a network protocol stack, an engineer observes that data undergoes multiple transformations at different OSI layers before transmission. Which sequence correctly represents these transformations?

A Data → Segments → Packets → Frames → Bits

B Data → Packets → Segments → Frames → Bits

C Bits → Frames → Packets → Segments → Data

D Data → Frames → Packets → Segments → Bits

Correct Answer: A. Data → Segments → Packets → Frames → Bits

EXPLANATION

The correct sequence during encapsulation is: Layer 7 (Data) → Layer 4 (Segments) → Layer 3 (Packets) → Layer 2 (Frames) → Layer 1 (Bits).

Test

Q.18 Hard OSI Model

A financial institution requires compliance with data protection regulations that mandate end-to-end encryption. At which OSI layer(s) should encryption be implemented to ensure comprehensive protection while maintaining optimal performance?

A Layer 1 only; encrypt all physical signals

B Layer 2 only; encrypt all frames

C Layers 6-7 for end-to-end encryption, with optional Layer 2 for link-level encryption

D Layer 4 only; encrypt all transport layer data

Correct Answer: C. Layers 6-7 for end-to-end encryption, with optional Layer 2 for link-level encryption

EXPLANATION

End-to-end encryption is best implemented at Layer 6-7 (Presentation/Application) to ensure data remains encrypted from source to destination. Additional Layer 2 encryption protects link-level transmission.

Test

Q.19 Hard OSI Model

A security researcher discovers that malware on an infected system is manipulating ARP (Address Resolution Protocol) responses. At which OSI layer does this attack occur, and what is its impact on network communication?

A Layer 1; causes physical signal degradation

B Layer 2; enables MAC spoofing and man-in-the-middle attacks by mapping IP addresses to incorrect MAC addresses

C Layer 3; disrupts IP routing tables

D Layer 4; blocks port-based filtering

Correct Answer: B. Layer 2; enables MAC spoofing and man-in-the-middle attacks by mapping IP addresses to incorrect MAC addresses

EXPLANATION

ARP operates at Layer 2 (Data Link Layer). ARP spoofing maps IP addresses to attacker-controlled MAC addresses, enabling man-in-the-middle attacks and traffic redirection.

Test

Q.20 Hard OSI Model

During a network migration, an organization must maintain service continuity while transitioning from IPv4 to IPv6. At which OSI layer would the primary compatibility challenges arise, and what approach would address them?

A Layer 2; requires replacing all switches

B Layer 3; may require dual-stack implementation or tunneling protocols

C Layer 4; TCP and UDP must be completely rewritten

D Layer 7; all applications must be redesigned

Correct Answer: B. Layer 3; may require dual-stack implementation or tunneling protocols

EXPLANATION

IPv4 and IPv6 operate at Layer 3 (Network Layer). Dual-stack (running both simultaneously) or tunneling (encapsulating IPv6 in IPv4) addresses compatibility during migration.

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