Cisco CCNA OSI and TCP/IP Models 3

Question 1

Which OSI layer is responsible for flow control and error recovery using mechanisms like windowing and acknowledgments?

Accepted Answer

Transport (Layer 4)

Answer

The Transport layer (Layer 4) provides end-to-end flow control via windowing and reliable delivery through acknowledgment and retransmission.

Question 2

How many layers does the TCP/IP model have compared to the OSI model?

Accepted Answer

The TCP/IP model has 4 layers; OSI has 7

Answer

The TCP/IP model has 4 layers (Application, Transport, Internet, Network Access), while the OSI model has 7 layers.

Question 3

A technician captures traffic and sees a PDU with source and destination MAC addresses but no IP header. At which OSI layer was this PDU created?

Accepted Answer

Layer 2 - Data Link

Answer

MAC addresses are used at Layer 2 (Data Link), and frames at this layer do not contain IP headers.

Question 4

Which protocol operates at the TCP/IP Application layer and is used to resolve hostnames to IP addresses?

Accepted Answer

DNS

Answer

DNS (Domain Name System) operates at the Application layer of the TCP/IP model and resolves fully qualified domain names to IP addresses.

Question 5

During de-encapsulation on a receiving host, in what order does processing occur?

Accepted Answer

Layer 1 → Layer 2 → Layer 3 → Layer 4 → Layer 7

Answer

De-encapsulation on the receiving host processes data from the Physical layer (1) upward through the layers to the Application layer (7).

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