What does the DOCSIS Physical Layer specify?

The DOCSIS (Data Over Cable Service Interface Specification) Physical Layer is primarily concerned with the modulation and access techniques used for transmitting data over cable networks. This specification outlines how data is physically transmitted over coaxial and fiber optic cables, including the modulation schemes that enable the efficient use of the available bandwidth. By defining the physical means of data transport, such as the types of modulation (for example, QAM - Quadrature Amplitude Modulation) and the methods of channel access (like frequency division multiple access), it ensures that devices can communicate effectively across a cable infrastructure.

The other options pertain to different layers or aspects of networking. Data encryption methods, for instance, are related to ensuring the privacy and security of the data being transmitted, but they are not defined within the Physical Layer specifications. Similarly, IP address allocation is part of the network layer, concerned with the assignment of addresses for routing data effectively, rather than the physical transmission. Network security protocols cover a broad range of security measures and standards applicable across multiple layers of networking but are also not directly defined in the context of the DOCSIS Physical Layer. Thus, the correct choice encapsulates the core focus of the DOCSIS Physical Layer in handling the modulation and access techniques essential for