Final answer:
The correct answer is option 4) Message security. Syslog defines message transmission, format, and handling, but not the security of messages, which must be enhanced using additional protocols.
Step-by-step explanation:
The correct answer is option 4) Message security. Syslog is a standard for message logging that allows for the collection and storage of log data. In syslog protocol, message transmission refers to how messages are sent from the source to the syslog server, while message format defines the structured layout of the log message, which usually includes a timestamp, a host IP address, and the actual message content. Message handling involves the processing of these messages by the syslog daemon or server, which includes classifying the messages by severity and writing them to the appropriate log files.
However, syslog does not inherently provide message security; this means it does not define how to secure the transmission against interception or modification. Transport of syslog messages can be secured using other protocols such as TLS, but this is not part of the base syslog protocol itself. Therefore, message security is not defined by syslog, making option 4 the correct answer.