CCP TCP/IP & OSI Model Layers 3 — Questions and Answers
Question 1: Which OSI layer handles the syntax and semantics of data exchanged, including encryption and compression?
- Session layer
- Presentation layer (Correct answer)
- Application layer
- Transport layer
Correct answer: Presentation layer
The Presentation layer (Layer 6) is responsible for data format translation, encryption, and compression.
Question 2: UDP is preferred over TCP in applications where:
- Data integrity is the top priority
- Low latency matters more than guaranteed delivery (Correct answer)
- Connection state must be maintained
- Packets must arrive in order
Correct answer: Low latency matters more than guaranteed delivery
UDP's connectionless, low-overhead nature makes it ideal for real-time applications like VoIP and video streaming where speed outweighs reliability.
Question 3: What is the purpose of the ICMP protocol in the TCP/IP suite?
- Assigning IP addresses dynamically
- Translating domain names to IP addresses
- Reporting network errors and diagnostic information (Correct answer)
- Securing data with encryption
Correct answer: Reporting network errors and diagnostic information
ICMP (Internet Control Message Protocol) is used to send error messages and operational information about network conditions, as used by ping and traceroute.
Question 4: In OSI terminology, the unit of data at the Data Link layer is called a:
- Segment
- Packet
- Frame (Correct answer)
- Datagram
Correct answer: Frame
The Protocol Data Unit (PDU) at the Data Link layer is called a frame, which includes the MAC header and trailer.
Question 5: Which field in the IPv4 header identifies the higher-layer protocol (e.g., TCP, UDP) carried in the payload?
- Type of Service
- Protocol (Correct answer)
- Fragment Offset
- Identification
Correct answer: Protocol
The Protocol field in the IPv4 header indicates which transport-layer protocol (TCP=6, UDP=17, ICMP=1) is encapsulated.
Question 6: Sliding window flow control in TCP is designed to:
- Prevent IP packet fragmentation
- Allow multiple unacknowledged segments to be in transit simultaneously (Correct answer)
- Limit the number of TCP connections on a port
- Randomize the initial sequence number
Correct answer: Allow multiple unacknowledged segments to be in transit simultaneously
The sliding window mechanism allows a sender to transmit multiple segments before receiving acknowledgments, improving throughput over high-latency links.
Question 7: What distinguishes a Layer 2 switch from a Layer 3 switch?
- A Layer 3 switch can forward packets based on IP addresses in addition to MAC addresses (Correct answer)
- A Layer 2 switch supports VLANs while a Layer 3 switch does not
- A Layer 3 switch uses CSMA/CD and a Layer 2 switch uses token ring
- A Layer 2 switch operates wirelessly and a Layer 3 switch is wired only
Correct answer: A Layer 3 switch can forward packets based on IP addresses in addition to MAC addresses
A Layer 3 switch performs routing by examining IP addresses, enabling inter-VLAN routing, while a Layer 2 switch forwards only based on MAC addresses.
CCP TCP/IP & OSI Model Layers 3
Which OSI layer handles the syntax and semantics of data exchanged, including encryption and compression?