What type of packet does the server send in response to a client’s connection request?

When a client initiates a connection request to a server in the context of the Transmission Control Protocol (TCP), the server's response is a SYN/ACK packet. This is part of the three-way handshake process that establishes a TCP connection.

Initially, the client sends a SYN packet to indicate a desire to establish a connection. Upon receiving this SYN packet, the server responds not only to acknowledge the receipt of the SYN but also to indicate that it is ready to establish a connection. Therefore, it sends a SYN/ACK packet, combining both the synchronization (SYN) to request a connection and acknowledgment (ACK) to confirm the receipt of the client's request.

The SYN/ACK packet signifies that the server is actively participating in the connection establishment process and is prepared to communicate further. Following this, the client will send an ACK packet back to the server to complete the handshake, resulting in a fully established connection.

The other types of packets listed are not relevant in this context: an ACK packet is simply an acknowledgment of received data but does not initiate a connection; a connection packet is not a formally defined packet type in the TCP/IP suite; and a data packet pertains to the actual data transfer after the connection has been established, not the initial handshake process