Which of the following does a SYN scan typically check for?

• A. Open ports and services on a target machine.
• B. User credentials on remote systems.
• C. The operating system type.
• D. The physical location of the target.

Answer: (A)

A SYN scan is a TCP port-scanning technique that checks which ports are open by sending a SYN packet to each port and observing the response. If a port replies with SYN-ACK, that port is open and listening for connections; many scanners then send RST to avoid completing the full three-way handshake, keeping the scan fast and somewhat stealthy. If a port replies with RST, the port is closed; if there’s no reply, the port is filtered by a firewall or network device. Because of this behavior, the primary outcome of a SYN scan is a map of open ports (and, by extension, which services might be reachable on those ports).

The other options aren’t what a SYN scan is designed to reveal: checking user credentials requires authentication attempts, not port probing; determining the operating system involves OS fingerprinting or banner/granular analysis beyond the basic port-state check; and locating the physical position of the target is outside the scope of port scanning and would rely on other network-diagnostic techniques.