Exam with correct answers
What does the OSI model stand for and what are
the seven layers? - CORRECT ANSWERS ✔✔Open
Systems Interconnection Reference Model
Layer 7 = Application
Layer 6 = Presentation
Layer 5 = Session
Layer 4 = Transport
Layer 3 = Network
Layer 2 = Data Link
Layer 1 = Physical
Describe layer 1 of the OSI model - CORRECT
ANSWERS ✔✔Physical layer -- signaling, cabling,
connections
No protocols
Examples of layer 1 issues and solutions - CORRECT
ANSWERS ✔✔Fix cabling, punch-downs, etc.
,Run loopback tests, test/replace cables, swap
adapter cards
Loopback test - CORRECT ANSWERS ✔✔A diagnostic
procedure that verifies the integrity of a
communication pathway by sending a signal from a
device and returning it to the same device
Describe layer 2 of the OSI model - CORRECT
ANSWERS ✔✔Data Link layer, the basic network
"language", the foundation of communication
* MAC address on Ethernet
The "switching" layer
Describe layer 3 of the OSI model - CORRECT
ANSWERS ✔✔Network layer, the "routing layer"
* Internet Protocol (IP)
* Fragments frames to traverse different networks
Describe layer 4 of the OSI model - CORRECT
ANSWERS ✔✔Transport layer, the "post office"
layer, parcels and lettings from one side of the
network to the other
* TCP & UDP
,Describe layer 5 of the OSI model - CORRECT
ANSWERS ✔✔Session layer, communication
between devices (start, stop, restart)
* Control protocols, tunneling protocols
Describe layer 6 of the OSI model - CORRECT
ANSWERS ✔✔Presentation layer
* Character encoding
* Application encryption
* Often combined with layer 7, the application layer
Describe layer 7 of the OSI model - CORRECT
ANSWERS ✔✔Application layer, the layer we see
* HTTP, FTP, DNS, POP3
OSI model mapped to real-world - CORRECT
ANSWERS ✔✔Layer 7 = Your eyes
Layer 6 = Application encryption (SSL/TLS)
Layer 5 = Control protocols, tunneling protocols
Layer 4 = TCP segment, UDP datagram
Layer 3 = IP Address, Router, Packet
Layer 2 = Frame, MAC address, Extended Unique
Identifier (EUI-48, EUI-64), Switch
Layer 1 = Cables, fiber, and the signal itself
, Real-world example of the OSI model - CORRECT
ANSWERS ✔✔Application: https://mail.google.com
Presentation: SSL encryption
Session: Link the presentation to the transport
Transport: TCP encapsulation
Network: IP encapsulation
Data Link: Ethernet
Physical: Electrical signals
Router - CORRECT ANSWERS ✔✔- Routes traffic
between IP subnets
- OSI layer 3 devices
- Routers inside of switches sometimes called
"layer 3 switches"
- Often connects diverse network types
* LAN, WAN, copper, fiber
Switch - CORRECT ANSWERS ✔✔- Forwards traffic
based on data link address
- May provide PoE (Power over Ethernet)