Welcome to today’s CompTIA Network+ practice test!
Today’s practice test is based on subdomain 1.1 (Explain concepts related to the Open Systems Interconnection (OSI) reference model) from the CompTIA Network+ N10-009 objectives.
This beginner-level practice test is inspired by the CompTIA Network+ (N10-009) exam and is designed to help you reinforce key networking concepts on a daily basis.
These questions are not official exam questions, nor are they brain dumps, but they reflect topics and scenarios relevant to the Network+ certification exam objectives. Use them to test your knowledge, identify areas for improvement, and build daily networking habits.
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Results
#1. Which of the following best describes a primary difference between the Transport and Session layers of the OSI model?
#2. A cloud administrator is configuring security group rules to restrict traffic by source IP address and destination port. Which OSI layers are directly impacted?
#3. Which of the following protocols operates primarily at the Transport layer of the OSI model?
#4. Users report they cannot access secure websites. Investigation reveals TCP port 443 is blocked. Which OSI layers are likely involved in this issue?
#5. Which of the following is a function of the OSI model’s Presentation layer?
#6. A technician replaces a damaged Ethernet cable. Which OSI layer does this action primarily impact?
#7. Which OSI layer does the IP protocol belong to?
#8. Which of the following best differentiates Layer 2 from Layer 3 of the OSI model?
#9. A firewall is configured to drop ICMP traffic. What OSI layer function is directly affected?
#10. Which of the following is a typical example of an Application layer protocol?
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To view CompTIA Network+ practice tests on other days, click here.To view answers and explanations for today’s questions, expand the Answers accordion below.
Answers
| Number | Answer | Explanation |
|---|---|---|
| 1 | B | Which of the following best describes a primary difference between the Transport and Session layers of the OSI model? A. The Transport layer initiates sessions, while the Session layer handles encryption: The Session layer initiates and manages sessions, and encryption is typically handled at the Presentation layer (or by specific security protocols at various layers). B. The Transport layer ensures data reliability, while the Session layer manages dialog control Transport Layer: Focuses on end-to-end communication, ensuring data delivery, error recovery, and flow control (e.g., TCP ensures reliability). Session Layer: Establishes, manages, and terminates connections (sessions) between applications. “Dialog control” refers to managing who can transmit data at a certain time and coordinating communication between applications. C. The Transport layer compresses data, while the Session layer routes packets: Compression is a Presentation layer function. Routing packets is a Network layer function. D. The Transport layer defines IP addressing, while the Session layer manages port numbers: IP addressing is defined at the Network layer. Port numbers are managed at the Transport layer. |
| 2 | C | A cloud administrator is configuring security group rules to restrict traffic by source IP address and destination port. Which OSI layers are directly impacted? A. Layers 1 and 2: Layer 1 (Physical) deals with physical transmission (cables, signals). Layer 2 (Data Link) deals with MAC addresses and local network communication. Neither directly involves IP addresses or port numbers for filtering. B. Layers 4 and 7: While Layer 4 is correct for ports, Layer 7 (Application) deals with application-specific protocols and data formats, which are generally beyond the scope of basic security group rules that filter by IP and port. C. Layers 3 and 4 Layer 3 (Network Layer): Deals with IP addresses (source IP address in this case), which are used for logical addressing and routing. Layer 4 (Transport Layer): Deals with port numbers (destination port), which identify specific applications or services on a host. Security groups commonly filter traffic based on both of these. D. Layers 5 and 6: Layer 5 (Session) manages communication sessions. Layer 6 (Presentation) handles data formatting and encryption/decryption. These layers are not directly involved in basic IP address and port filtering. |
| 3 | B | Which of the following protocols operates primarily at the Transport layer of the OSI model? A. IP (Internet Protocol) : Operates at the Network Layer (Layer 3). It’s responsible for logical addressing (IP addresses) and routing packets across networks. B. TCP (Transmission Control Protocol): TCP is a core Transport layer protocol responsible for reliable, ordered, and error-checked delivery of a stream of bytes between applications running on hosts. It manages segments, flow control, and congestion control. C. HTTP (Hypertext Transfer Protocol): Operates at the Application Layer (Layer 7). It’s used for fetching resources like web pages. D. DNS (Domain Name System): Operates primarily at the Application Layer (Layer 7). It translates human-readable domain names into IP addresses. |
| 4 | B | Users report they cannot access secure websites. Investigation reveals TCP port 443 is blocked. Which OSI layers are likely involved in this issue? A. Layers 3 and 5: Layer 3 (Network) deals with IP addresses, not specific ports being blocked for secure websites. Layer 5 (Session) manages sessions, but the fundamental block is at the port level, preventing the session from even establishing. B. Layers 4 and 7: Layer 4 (Transport Layer): TCP port 443 is a Transport layer concept. When it’s blocked, it directly impacts the ability of applications to establish connections over this specific port. Layer 7 (Application Layer): Secure websites use HTTPS, which operates at the Application layer. HTTPS relies on TCP port 443 at the Transport layer. If port 443 is blocked, the Application layer protocol (HTTPS) cannot function, preventing access to secure websites. C. Layers 2 and 6: Layer 2 (Data Link) deals with MAC addresses and local network access. Layer 6 (Presentation) deals with data formatting and encryption/decryption (like SSL/TLS which HTTPS uses), but the block itself is at the port, preventing the data from reaching this layer. D. Layers 1 and 7: Layer 1 (Physical) deals with physical connectivity. While Layer 7 is involved, Layer 1 is too low-level for a port-specific blocking issue. |
| 5 | D | Which of the following is a function of the OSI model’s Presentation layer? A. MAC address filtering: This is a function of the Data Link layer (Layer 2), dealing with physical addressing on a local network segment. B. Route selection: This is a function of the Network layer (Layer 3), determining the optimal path for data across different networks. C. Flow control and sequencing: These are primary functions of the Transport layer (Layer 4), ensuring reliable and ordered delivery of data between end systems. D. Data encryption and translation: The Presentation layer (Layer 6) is responsible for ensuring that data is in a format that the receiving application can understand. This includes tasks like data encryption/decryption, compression/decompression, and data format translation (e.g., converting ASCII to EBCDIC). |
| 6 | A | A technician replaces a damaged Ethernet cable. Which OSI layer does this action primarily impact? A. Layer 1 – Physical: The Physical layer deals with the actual physical medium of transmission, such as cables, connectors, and electrical signals. Replacing a damaged Ethernet cable directly addresses an issue at this fundamental layer. B. Layer 2 – Data Link: This layer deals with MAC addresses, error detection, and frame transmission over a local network, not the physical cable itself. C. Layer 3 – Network: This layer handles IP addresses and routing packets between networks, which is a higher-level function than dealing with the cable. D. Layer 4 – Transport: This layer manages end-to-end communication, port numbers, and data reliability (like TCP/UDP), far removed from the physical cabling. |
| 7 | C | Which OSI layer does the IP protocol belong to? A. Layer 1 (Physical): This layer deals with the physical transmission of raw bit streams over the medium (e.g., cables, connectors, electrical signals). B. Layer 2 (Data Link): This layer handles physical addressing (MAC addresses), error detection, and frame transmission within a local network segment. C. Layer 3: IP (Internet Protocol) is fundamentally a Network Layer (Layer 3) protocol. It is responsible for logical addressing (IP addresses) and routing packets across different networks (inter-networking). D. Layer 4 (Transport): This layer manages end-to-end communication between applications, including flow control, error recovery, and port numbers (e.g., TCP, UDP) |
| 8 | B | Which of the following best differentiates Layer 2 from Layer 3 of the OSI model? A. Layer 2 uses IP addresses; Layer 3 uses MAC addresses: This is incorrect. Layer 2 uses MAC addresses, and Layer 3 uses IP addresses. The statement swaps them. B. Layer 2 forwards data via switches; Layer 3 routes data using IP addresses Layer 2 (Data Link Layer): Operates on a local network segment using MAC addresses for addressing and is associated with devices like switches that forward data frames within that segment. Layer 3 (Network Layer): Operates across different networks using logical IP addresses for addressing and is associated with devices like routers that route data packets between these networks. C. Layer 2 manages port numbers; Layer 3 handles session setup: This is incorrect. Port numbers are managed at Layer 4 (Transport), and session setup is handled at Layer 5 (Session). D. Layer 2 translates data formats; Layer 3 encrypts packets: This is incorrect. Data format translation and encryption are functions of Layer 6 (Presentation). Neither Layer 2 nor Layer 3 primarily handles these tasks |
| 9 | B | A firewall is configured to drop ICMP traffic. What OSI layer function is directly affected? A. Layer 1: This layer deals with the physical transmission of data (cables, signals). Dropping ICMP traffic is a logical filtering decision, not a physical one. B. Layer 3: ICMP (Internet Control Message Protocol) is a protocol that operates at the Network Layer (Layer 3) of the OSI model. It’s used for diagnostic functions and reporting errors concerning the delivery of IP packets (e.g., ping commands use ICMP). When a firewall drops ICMP traffic, it’s directly affecting Layer 3 communication. C. Layer 4: This layer deals with end-to-end communication between processes using port numbers (like TCP and UDP). ICMP does not use port numbers. D. Layer 6: This layer (Presentation) deals with data formatting, encryption, and translation. Dropping ICMP traffic is a network control function, not related to data presentation |
| 10 | D | Which of the following is a typical example of an Application layer protocol? A. TCP (Transmission Control Protocol): Operates at the Transport layer (Layer 4). It provides reliable, connection-oriented data transmission for applications. B. UDP (User Datagram Protocol): Operates at the Transport layer (Layer 4). It provides unreliable, connectionless data transmission, often used for real-time applications. C. ARP (Address Resolution Protocol): Operates primarily at the Data Link layer (Layer 2), though it has components that interact with the Network layer. Its main function is to map IP addresses to MAC addresses on a local network. D. FTP (File Transfer Protocol): FTP operates at the Application layer (Layer 7). It’s a high-level protocol that directly interacts with software applications to enable users to transfer files between computers on a network. |