A client is transmitting a large amount of data to a server. During this process, the server sets the window size to zero. What is the likely cause of this issue?

In TCP, the receive window field in the ACK segment advertises how many bytes the receiver can currently buffer. When the server's receive buffer is full, it sets the window size to zero to implement flow control, forcing the client to stop sending data until a window update is received. This is a normal TCP mechanism to prevent buffer overflow at the receiving end.

A connection reset is signaled by the RST flag in a TCP segment, not by a window size of zero - a zero window pauses data flow without terminating the session.

The window size field is set by the receiver (server), not the sender (client) - a client buffer exhaustion would affect the client's own advertised window, not the server's.

Maximum segment size (MSS) governs the largest payload per TCP segment and is negotiated during the handshake; it is unrelated to the receive buffer capacity advertised by the window size field.