Select ALL statements that accurately describe the transport layer and protocol trade-offs in the refresher.

### Why this is right - **The Ethernet header carries the physical next-hop address.** The refresher distinguishes this local next-hop addressing role from the ultimate source and destination carried in the IP header. - **The Internet Protocol (IP) header carries the ultimate source and destination addresses.** This is the addressing role assigned to IP in the slide's packet breakdown. - **The transport header describes how the data should be sent and contains the Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) header.** The transport layer carries the protocol information reviewed in the module. - **End devices must maintain state for Transmission Control Protocol (TCP) sessions.** TCP creates sessions, and devices track them to support reliable communication. ### The concept The packet headers serve different purposes. Ethernet identifies the physical next hop, IP identifies the ultimate endpoints, and the transport header carries information used to deliver data to an application and govern its transmission. TCP's larger header and session state support reliable delivery, while UDP's smaller header leaves more room for payload and avoids explicit session creation. ### The other options - **D. A larger Transmission Control Protocol (TCP) header leaves more room for payload than a smaller User Datagram Protocol (UDP) header.**: This reverses the stated trade-off. A larger header limits the total payload size, which is why UDP's smaller header can leave more room. ### Terms - **Ethernet**: The link-layer technology whose header identifies the physical next hop in the refresher's packet model. - **IP**: Internet Protocol. The protocol whose header carries ultimate source and destination addresses. - **TCP**: Transmission Control Protocol. A reliable transport protocol that creates tracked sessions. - **UDP**: User Datagram Protocol. A best-effort transport protocol with a smaller, simpler header. - **Transport layer**: The layer that describes how data should be sent between applications. - **Header**: Control information attached to data. - **Payload**: The application data carried by a packet. - **Session state**: Information end devices maintain about an active TCP communication. ### Remember Separate the addressing jobs: Ethernet names the next hop, IP names the endpoints, and transport information supports application delivery.