Which layer should be investigated if packets are arriving at the server but no information is returned to the client?

The situation described involves packets arriving at the server but no information being sent back to the client. This points to a potential issue within the Transport Layer. The Transport Layer is responsible for end-to-end communication and data transfer between devices, ensuring that data packets are successfully delivered. If packets are reaching the server, it’s likely that the physical and data link layers are functioning correctly since the client can send packets.

However, if no information is being returned to the client, this could signify problems with the protocol used in the Transport Layer, such as TCP or UDP. Issues with acknowledgment (ACK) packets or improper sequencing of packets can prevent successful replies to the client. Furthermore, firewalls or other security devices can block return packets at this layer, leading to a situation where the server receives requests but does not respond.

Understanding the role of the Transport Layer is crucial, as it directly influences the reliability of communications and the ability of servers to send responses back to clients. This distinguishes it from the other layers—like the Data Link Layer, which handles local network connections, or the Network Layer, which deals with routing and addressing data packets. The Session Layer, while involved in establishing connections and managing sessions, does not directly manage the flow of packets or responses