I believe that the correct answer is that how it should be configured depends on how you want it to work. If you want to connect to the console and to see the log output then you should configure logging console. If you do not want to send logging output to the console then configure no logging console.
I have a customer that has a lot of remote offices. There are not network staff at the remote offices and there is no reason why someone would connect to the console in the remote office. So their standard config for routers at remote offices is no logging console. In this way they are sure that the router will spend no processing cycles in attempting to send any output to the console.
The question about what to do about debug output is perhaps interesting. The previous observation that debug output can put heavy load on the console output is quite correct. I know people who routinely configure no logging console when they are about to enable debug. I believe that this is an over reaction. If you configure logging console information this will control the severity level of messages sent to the console. It will allow most log messages to be displayed on the console and will not display debug messages on the console. I believe that this is a better solution of how to minimize the impact of debug.
As others have it really depends what you need to have that on for , if you have no modem on the router or switch and very rarely plug into the console i would leave it off . This is out of a 6500 best practices guide.
no logging console-By default, all system messages are sent to the system console. Console logging is a high-priority task in Cisco IOS Software. This function was primarily designed to provide error messages to the system operator before a system failure. Disable console logging in all device configurations in order to avoid a situation in which the router/switch can hang while the device waits for a response from a terminal. But console messages can be useful during trouble isolation. In these instances, enable console logging. Issue the logging console level command in order to obtain the desired level of message logging. Logging levels are from 0 to 7.
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