protocol behaviours and OSI layers Flashcards
(13 cards)
What are the 7 layers of the OSI model (from top to bottom)?
Application, Presentation, Session, Transport, Network, Data Link, Physical
What is the primary function of the Transport Layer?
Provides reliable or unreliable delivery; includes error recovery, flow control (e.g., TCP, UDP)
What protocol provides reliable, connection-oriented delivery at the transport layer?
TCP (Transmission Control Protocol)
What protocol provides connectionless, unreliable delivery at the transport layer?
UDP (User Datagram Protocol)
Which OSI layer is responsible for routing and logical addressing?
Network Layer (e.g., IP, routers)
Q: Which layer handles framing, MAC addressing, and error detection?
A: Data Link Layer (e.g., Ethernet, PPP)
Q: What is TCP Slow Start?
A: TCP starts with a small congestion window and increases it exponentially until a threshold is reached or congestion occurs.
Q: What is the purpose of TCP Congestion Avoidance?
A: To incrementally increase the congestion window linearly to prevent congestion collapse
Q: What does Fast Retransmit do in TCP?
A: Retransmits a lost packet after receiving 3 duplicate ACKs — faster than waiting for timeout
Q: What is the role of PPP (Point-to-Point Protocol)?
A: Encapsulates Layer 3 packets over point-to-point links; supports byte/bit stuffing and error detection
Q: What is Bit Stuffing?
A: A technique used to ensure that flag sequences in the data stream don’t appear as actual data (insert a 0 after 5 consecutive 1s)
Q: What is Byte Stuffing in PPP?
A: Inserts escape sequences before special bytes (e.g., 0x7E, 0x7D) to avoid confusion with control characters
Q: What protocol maps client MAC addresses to IP addresses?
A: ARP (Address Resolution Protocol)
