ccna 200-301 pdf volume 2

ccna 200-301 pdf volume 2.On Cisco network devices, the syslog protocol begins by sending system messages and debug output messages to a local logging process inside the device. The logging process manages these messages and outputs according to the configuration of the device. For example, syslog messages can be sent along the network to an external syslog server. These messages can then be retrieved without having to access the real device. Log messages and output stored on the external server can be converted into different report forms for easy reading.Alternatively, syslog messages can be sent to the internal cache. Messages sent to the internal cache can only be viewed through the CLI of the device. Finally, the network administrator can also specify that certain types of system messages are sent to different destinations. For example, the device can be configured to forward all system messages to an external syslog server. However, debug-level messages need to be forwarded to the internal cache and can only be accessed by the administrator through the CLI. Cisco routers can log information based on configuration changes, ACL violations, interface status, and other events. Cisco routers can also send logging messages to different devices. Routers can be configured to send syslog messages to one or more of the following locations.Log caching-Because log messages can be stored in the router's memory for a period of time, log caching is a useful security tool. However, events will be cleared after the router reboots.Console One-by-one By default, console logging is turned on. After log messages are sent to the console, Bea can view them when she connects to the router's console port to modify or test the router using terminal emulation software.Terminal lines - An EXEC session can be configured on any terminal line to receive log messages. Similar to console logging, log messages for terminal lines are not stored by the router and are therefore only of value to users on that line.syslog server - Cisco routers can be configured to forward log messages to an external syslog service. This service can be deployed on any number of servers or workstations, including Microsoft Windows and UNIX-based systems. Because syslog provides long-term storage capability and is the hub for all router messages, it is the more commonly used logging tool.2.3.3.3 syslog MessagesWhen a network event occurs, the Cisco device generates syslog messages. Each syslog message contains a severity and facility o A smaller value for the severity level indicates a more serious syslog alert. The severity level of the message can be used to control where each type of message is displayed (for example, on the console or at another destination). Each level of syslog has its own meaning.2.3 Monitoring and Managing Devices 45Warning, error, critical, alarm, and emergency levels: these messages are error messages about software or hardware failures; these types of messages indicate that device functionality is affected. The severity of the problem determines the syslog level applied.