Encapsulation order across the stack: When data moves down the networking stack for transmission, what is the correct encapsulation order from highest-level data to the actual signals on the medium?

Introduction / Context:
Encapsulation wraps higher-layer information in lower-layer headers/trailers as data descends the stack. Getting the order right helps troubleshoot where problems occur (e.g., TCP vs IP vs Ethernet) and clarifies what each layer contributes.

Given Data / Assumptions:

• Application payload is called “data.”
• Transport adds a header to create a segment (TCP) or datagram (UDP).
• Network adds IP to create a packet.
• Data link (e.g., Ethernet) adds a frame header/trailer.
• Physical transmits bits on the medium.

Concept / Approach:

The canonical progression is: Data (Layer 7–5 payload) → Segment (Layer 4) → Packet (Layer 3) → Frame (Layer 2) → Bits (Layer 1). Each layer adds control information relevant to its function (reliability, addressing, media access).

Step-by-Step Solution:

Verification / Alternative check:

Packet captures show nested headers: Ethernet outside, then IP, then TCP/UDP, then application data, matching the sequence above.

Why Other Options Are Wrong:

Options that swap frame/packet or segment/data contradict OSI/TCP-IP encapsulation rules.

“Segment, data…” places payload after transport encapsulation, which is incorrect.

Common Pitfalls:

Confusing “packet” and “frame” terminology; forgetting that at Layer 4 TCP is a segment while UDP is often called a datagram.

Final Answer:

Data, segment, packet, frame, bit