In a TCP header, which control flag indicates that the receiver should deliver the data immediately to the receiving application without waiting for buffers to fill?
The PSH flag instructs the receiving TCP stack to bypass buffering and push all accumulated data directly to the application layer process.
What is the purpose of the TCP 3-way handshake before data transfer begins?
The TCP three-way handshake (SYN, SYN-ACK, ACK) establishes the connection, synchronizes sequence numbers, and confirms bidirectional participation. TLS key negotiation is separate from the TCP handshake. Thus A and B are correct.
In TCP Reno, what event causes the Congestion Window (cwnd) to reset completely back to 1 Maximum Segment Size (MSS)?
A timeout indicates severe network congestion: ssthresh is set to cwnd/2, and cwnd collapses back to 1 MSS, restarting in the Slow Start phase.
Which application layer protocol uses Port 110 to download emails from a mail server to a local client?
POP3 uses TCP port 110 (or 995 for POP3S) to download emails to a single client device, traditionally deleting them from the mail server.
Which application layer protocol uses Port 143 to access and manage email messages stored centrally on a mail server across multiple devices?
IMAP4 (port 143, or 993 for IMAPS) keeps messages synchronized on the remote server, allowing users to organize mail in folders across multiple client devices.