1.2 Explain devices, applications, protocols and services at their appropriate OSI layers.

Question 1

Layer 1

Answer 1

Layer 1 - The Physical Layer

• Signaling, cabling, connectors

Question 2

Layer 2

Answer 2

Layer 2 - Data Link Layer
• MAC (Media Access Control) address on Ethernet
• The “switching” layer

Question 3

Layer 3

Answer 3

Layer 3 - The Network Layer
• The “routing” layer
• Fragments frames to traverse different networks in packets

Question 4

Layer 4

Answer 4

Layer 4 - Transport Layer
• The “post office” layer
• TCP (Transmission Control Protocol) and
UDP (UserDatagram Protocol)

Question 5

Layer 5

Answer 5

Layer 5 - Session Layer
• Communication management between devices
• Start, stop, restart
• Half-duplex, full-duplex
• Control protocols, tunneling protocols

Question 6

Layer 6

Answer 6

Layer 6 - Presentation Layer
• Character encoding
• Application encryption

Question 7

Layer 7

Answer 7

Layer 7 - Application Layer

• The layer we see - HTTP, FTP, DNS, POP3