OSI Layer Model
Subject: Computer Networks
Understanding 7 layers of Networking.
Sample Practice Questions
Question 1: Which OSI layer is responsible for translating data into a standard format, compression, and encryption?
- Application Layer
- Presentation Layer
- Session Layer
- Transport Layer
Explanation: The Presentation Layer ensures that data is in a readable format, handles encryption/decryption, and performs data compression.
Question 2: What is the primary function of the Address Resolution Protocol (ARP)?
- Map an IP address to a physical MAC address
- Map a domain name to an IP address
- Dynamically allocate IP addresses to hosts
- Route packets across subnets
Explanation: ARP resolves a known 32-bit IPv4 address into its corresponding 48-bit physical MAC address on a local area network.
Question 3: Which TCP port is commonly used for secure HTTP traffic (HTTPS)?
- 80
- 22
- 443
- 8080
Explanation: HTTPS (HTTP Secure) uses Transport Layer Security (TLS/SSL) to encrypt communications and listens by default on TCP port 443.
Question 4: Which layer of the OSI model is responsible for packet routing, logical addressing, and path determination?
- Data Link Layer
- Network Layer
- Transport Layer
- Physical Layer
Explanation: The Network Layer is responsible for routing packets across networks, logical addressing (IP addresses), and determining the best path.
Question 5: What is the main purpose of the Domain Name System (DNS) in computer networks?
- To encrypt network traffic
- To map human-readable domain names to numerical IP addresses
- To establish TCP connections between hosts
- To assign dynamic IP addresses to client devices
Explanation: DNS acts as the phonebook of the Internet, translating human-friendly domain names (e.g., example.com) to machine-readable IP addresses.
Question 6: The physical layer is concerned with ___________
- bit-by-bit delivery
- process to process delivery
- application to application delivery
- port to port delivery
Explanation: Physical layer deals with bit to bit delivery in networking. The data unit in the physical layer is bits. Process to process delivery or the port to port delivery is dealt in the transport layer. The various transmission mediums aid the physical layer in performing its functions.
Question 7: Which transmission media provides the highest transmission speed in a network?
- coaxial cable
- twisted pair cable
- optical fiber
- electrical cable
Explanation: Fiber optics is considered to have the highest transmission speed among the all mentioned above. The fiber optics transmission runs at 1000Mb/s. It is called as 1000Base-Lx whereas IEEE standard for it is 802.3z. It is popularly used for modern day network connections due to its high transmission rate.
Question 8: Bits can be sent over guided and unguided media as analog signal by ___________
- digital modulation
- amplitude modulation
- frequency modulation
- phase modulation
Explanation: In analog modulation, digital low frequency baseband signal (digital bit stream) is transmitted over a higher frequency. Whereas in digital modulation the only difference is that the base band signal is of discrete amplitude level. The bits are represented by only two frequency levels, one for high and one for low.
Question 9: The portion of physical layer that interfaces with the media access control sublayer is called ___________
- physical signalling sublayer
- physical data sublayer
- physical address sublayer
- physical transport sublayer
Explanation: The portion of physical layer that interfaces with the medium access control sublayer is Physical Signaling Sublayer. The main function of this layer is character encoding, reception, decoding and performs optional isolation functions. It handles which media connection the signal should be forwarded to physically.
Question 10: The physical layer provides __________
- mechanical specifications of electrical connectors and cables
- electrical specification of transmission line signal level
- specification for IR over optical fiber
- all of the mentioned
Explanation: Anything dealing with a network cable or the standards in use – including pins, connectors and the electric current used is dealt in the physical layer (Layer 1). Physical layer deals with bit to bit delivery of the data aided by the various transmission mediums.