Final answer:
To determine 'At what time was the ack for this first data-containing segment received?' we need the timestamp logs from the session, commonly found in network communications logs using TCP. The ack signals are verified in these logs which display sent and received times for data segments. Without specific logs or context, the exact time can't be provided.
Step-by-step explanation:
To answer the question, 'At what time was the ack for this first data-containing segment received?' we would need to refer to a specific scenario that includes a timestamp log of a transmission session between two devices or systems. In the context of networking, the acknowledgement (ack) refers to a signal that is sent to confirm the receipt of a data segment. The process usually involves protocols such as TCP (Transmission Control Protocol), where the sender awaits an ack signal for each segment sent, to ensure data integrity and proper sequence of delivery. If this is regarding a practical session or exercise, the timestamp for when the ack was received should be noted in either the sending or the receiving device's log files or output data. You should look through network logs detailing the communications between the sender and receiver. These logs would normally display the timestamps for when each segment was sent and when the corresponding ack was received. If this is a theoretical question or part of a simulation, typically, this information would be given within the scenario details. Unfortunately, without access to the specific context or network logs, it is not possible to provide the exact time the ack was received.