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Zorluk: OrtaEncapsulation and De-encapsulation

A system administrator monitors outbound network traffic generated by a local workstation initiating a secure shell (SSH) session to a remote server. As the application payload moves down the OSI model protocol stack on the source host, specific encapsulation processes take place. Which of the following statements accurately describe how the data unit is modified during this outbound encapsulation process? (Select TWO)

  1. The Transport layer encapsulates the application data into a segment by prepending a header containing source and destination port numbers.Cevap
  2. B
    The Network layer encapsulates the transport segment into a frame by prepending the IP header and appending a Frame Check Sequence (FCS) trailer.
  3. The Network layer encapsulates the transport layer segment into an IP packet by prepending source and destination IP addresses.Cevap
  4. D
    The Data Link layer replaces the IP addressing information with port numbers to convert the packet into a physical bitstream.

Cevap

The two correct statements are: (1) The Transport layer encapsulates the application data into a segment by prepending a header containing source and destination port numbers, and (2) The Network layer encapsulates the transport layer segment into an IP packet by prepending source and destination IP addresses.
Outbound encapsulation works down the OSI stack: Layer 4 (Transport) prepends port numbers to construct a segment, and Layer 3 (Network) prepends IP addresses to construct a packet. Both of these statements correctly describe PDU encapsulation.

Adım Adım Çözüm

1
Analyze Layer 4 (Transport Layer) Encapsulation
Application data receives a Layer 4 header (containing source and destination ports like SSH port 22), creating a Segment.
Transport layer encapsulation establishes process-to-process communication.
2
Analyze Layer 3 (Network Layer) Encapsulation
The Layer 4 Segment is passed down to Layer 3, where an IP header (containing source and destination IP addresses) is prepended, forming a Packet.
Network layer encapsulation provides logical host-to-host addressing across subnets.
3
Verify Data Link Layer (Layer 2) functions versus higher layer functions
Layer 2 prepends MAC addresses and appends a trailer (FCS) to form a Frame. It does not replace IP addresses or operate with port numbers.
Differentiates Layer 2 frame boundaries from Layer 3 packet and Layer 4 segment boundaries.

Anahtar Kavram

OSI Protocol Data Unit (PDU) Encapsulation Sequence
Tahmini Süre:1m 30s
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Konular

Encapsulation and De-encapsulation

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