ECCS3631: Unit 3 - OSI Model and TCP/IP

What organization created the OSI model?

ISO (International Organization for Standardization).

What was the purpose of the OSI model?

To allow interoperability between different vendor devices.

How does the OSI model simplify networking?

By dividing communication into layers.

What does the OSI model encourage in the industry?

Standardization of network protocols.

Why does the OSI model improve troubleshooting?

Problems can be isolated by layers.

What does layer independence mean?

Changes in one layer don’t affect others.

Which architectural model is the foundation for networking?

OSI reference model.

What does the layered approach allow vendors to do?

Build interoperable hardware and software.

What are the two groups of OSI layers?

Upper layers and lower layers.

What do the upper layers of OSI define?

Application-to-application communication rules.

How many layers are in the OSI model?

Seven.

Name OSI Layer 7.

Application.

Name OSI Layer 6.

Presentation.

Name OSI Layer 5.

Session.

Name OSI Layer 4.

Transport.

Name OSI Layer 3.

Network.

Name OSI Layer 2.

Data Link.

Name OSI Layer 1.

Physical.

Which OSI layer handles hardware addressing?

Data Link layer.

Which OSI layer transmits bits?

Physical layer.

What is the role of the Application layer?

User interaction with the network.

How does the Application layer interact with the OS?

Through APIs.

What is the function of the Presentation layer?

Data translation, encryption, and formatting.

Why is standard formatting important?

Ensures systems can read exchanged data.

What is the role of the Session layer?

Establishes, manages, and ends sessions.

What does dialogue control mean?

Determines simplex, half-duplex, or full-duplex communication.

What ensures separation of data between applications?

Session layer.

Example of Session layer function?

Supporting multiple browser sessions at once.

Which OSI layer provides synchronization?

Session layer.

What does the Transport layer do with data?

Segments and reassembles it.

What type of connection does TCP provide?

Reliable, connection-oriented.

What type of connection does UDP provide?

Unreliable, connectionless.

Which transport protocol uses acknowledgments?

TCP.

Which transport protocol is faster but less reliable?

UDP.

What is segmentation?

Breaking data into smaller units.

What is the main function of the Network layer?

Logical addressing and routing.

What device operates at Layer 3?

Router.

What happens when a router cannot find a route?

Packet is dropped.

What does a routing table store?

Destination networks and paths.

What is a default route?

A path used when no specific route exists.

What is path determination?

Selecting the best route for data.

What OSI layer ensures end-to-end delivery?

Network layer.

What addressing is used at Network layer?

IP addresses.

What does a router do with a packet?

Looks up destination IP and forwards accordingly.

What is the main role of the Data Link layer?

Frame creation and error handling.

What addresses are used at Layer 2?

MAC addresses.

What is a frame?

A formatted data unit at the Data Link layer.

What does the Physical layer transmit?

Raw bits.

What does the Data Link layer provide for LANs?

Reliable delivery using MAC addresses.

What type of topology information is handled at Layer 2?

Network topology and error notifications.

What is the difference between logical and physical addressing?

Logical = IP, Physical = MAC.

What medium does the Physical layer interact with?

Copper, fiber, or wireless media.

What is encapsulation at Layer 2?

Adding MAC headers and trailers.

What is the PDU at the Application layer?

Data.

What is the PDU at the Transport layer?

Segment.

What is the PDU at the Network layer?

Packet.

What is the PDU at the Data Link layer?

Frame.

What is the PDU at the Physical layer?

Bits.

What does encapsulation mean?

Wrapping data with protocol headers.

Why is encapsulation needed?

So each layer can process data properly.

What is de-encapsulation?

Removing headers at the receiving side.

What is the order of encapsulation from top to bottom?

Data â†' Segment â†' Packet â†' Frame â†' Bits.

Which layer adds the IP header?

Network layer.

How many layers are in the TCP/IP model?

Four or Five (depending upon the version).

What is the top layer of TCP/IP?

Application (Process) layer.

What is the third TCP/IP layer?

Internet layer.

Which OSI layers combine into TCP/IP’s Network Access layer?

Data Link and Physical.

What OSI layer corresponds to TCP/IP Internet layer?

Network.

What TCP/IP layer corresponds to OSI Transport layer?

Host-to-Host.

What TCP/IP layer corresponds to OSI Application, Presentation, and Session layers?

Process/Application layer.

Which OSI layer is closest to the user?

Application.

Which OSI layer is responsible for compression and encryption?

Presentation.

Which OSI layer manages sessions?

Session.

Which OSI layer establishes end-to-end communication?

Transport.

Which OSI layer makes routing decisions?

Network.

Which OSI layer uses MAC addresses?

Data Link.

Which OSI layer transmits signals?

Physical.

Which TCP/IP layer ensures data delivery between hosts?

Host-to-Host.

Which TCP/IP layer ensures interoperability across vendors?

Application.

Which TCP/IP layer handles physical addressing?

Network Access layer.