I am running kernel 4.1.15, sometimes in /var/log/messages i am getting series of ^@ characters. Normally the content is ok in /var/log/messages it is just for once for few seconds i got these junk characters. Any idea why?
That is the ASCII code for the Null Character
It shouldn't be an actual issue with logging. I would guess it is an issue with whatever program is outputting to /var/log/messages.
Some terminal emulator programs won't output character sequences correctly due to character encoding. Make sure you're using one (or connected with one) that matches your locale, such as UTF-8.