Final answer:
The source port for data returning from the server depends on the service provided, such as port 80 for HTTP, while the client's destination port matches the ephemeral port used to initiate the request. Network-layer datagrams contain the server's source IP and client's destination IP for proper routing.
Step-by-step explanation:
Understanding Port Numbers and IP Addresses
Regarding the question on port numbers and IP addresses, let's start with part a). When the server is sending data back to the client, the source port would typically be the port on which the server's service is running.
For example, if this is an HTTP service, the source port is likely to be port 80 for standard HTTP or port 443 for HTTPS. On the client side, the destination port would be the same ephemeral port that the client's process originally used to make the request to the server
.a) The source and destination port values in the segments flowing from the server back to the clients' processes can vary depending on the specific application.
For example, if the server is sending web pages back to the clients, the source port would typically be the well-known port number 80 for HTTP, while the destination port would be a randomly selected port number on the client side.
b) The IP addresses in the network-layer datagrams carrying the transport-layer segments also depend on the specific network setup. The server's IP address would be the source IP address, while the clients' IP addresses would be the destination IP addresses
For part b), the IP addresses in the network-layer datagrams would include the server's IP as the source IP address and the client's IP as the destination IP address.
These addresses facilitate the correct delivery of segments across the network, routing the information from the server back to the appropriate client device