Which layer of the TCP/IP model is responsible for routing messages through an internetwork?

The Internet layer of the TCP/IP model is responsible for routing messages through an internetwork. This layer facilitates the logical transmission of packets between devices across different networks. It does this by utilizing protocols such as Internet Protocol (IP), which provides addressing and routing capabilities.

Essentially, the Internet layer is equipped to make decisions about how packets are forwarded based on their destination IP addresses. It ensures that data can traverse various networks efficiently, potentially passing through multiple routers along the way. This routing capability is crucial for enabling communication across disparate network segments, thus forming the backbone of the Internet's functionality.

The other layers serve different functions: the Application layer handles high-level protocols and end-user services; the Transport layer focuses on end-to-end communication and reliability; and the Network access layer deals with physical network technologies and the details of how data is physically transmitted over a particular network medium. Understanding these distinctions is vital for grasping how data travels across networks and the specific role of each layer in the TCP/IP model.