In data communications: A single packet or unit of transmission at the data-link layer is referred to as what?

Introduction / Context:
The OSI model defines layers and the names of data units at each layer. At the data-link layer (Layer 2), network interface cards send and receive bounded units with headers and trailers.

Given Data / Assumptions:

• We are at the data-link layer, not the network or transport layers.
• Typical examples include Ethernet, 802.11, and PPP.

Concept / Approach:

The proper term for a data-link layer packet is a frame. Frames include addressing (MAC), control information, and a frame check sequence for error detection.

Step-by-Step Solution:

Verification / Alternative check:

Ethernet specifically defines an Ethernet frame with fields like Destination MAC, Source MAC, Type/Length, Payload, and FCS.

Why Other Options Are Wrong:

• Block/Group: generic terms, not OSI-specific.
• Path: refers to a route, not a data unit.
• None of the above: incorrect because 'Frame' is precise.

Common Pitfalls:

• Confusing network-layer 'packet' with data-link 'frame'.

Final Answer:

Frame.