OSI and TCP/IP Models Flashcards

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

Answer: Transport (Layer 4)

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

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

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

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

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?

Answer: Layer 2 - Data Link

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

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

Answer: DNS

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

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

Answer: Layer 1 → Layer 2 → Layer 3 → Layer 4 → Layer 7

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

Which two layers of the OSI model are combined into the Network Access layer of the TCP/IP model?

Answer: Physical and Data Link

The TCP/IP Network Access layer combines OSI's Physical layer (Layer 1) and Data Link layer (Layer 2) into a single layer.

Which OSI layer uses port numbers to identify specific applications or services on a host?

Answer: Transport (Layer 4)

The Transport layer (Layer 4) uses port numbers in TCP and UDP headers to multiplex multiple application streams on the same host.