Paresh - my understanding of the original post is that when she does show startup-config that no date is there. There is an explanation for this.

Narayan - the service timestamps is a good command and I agree that specifying datetime is better than the default of displaying uptime. But this command does not have anything to do with the date in the config file.

What does control the presence (or absence in this case) is whether the router has authoritative time at the time the config was changed or saved. The router can have authoritative time by use of the clock set command or by use of NTP. I believe that NTP is a much better solution.

So if the router really knows correct time it will put the time stamp into the config. And if the router does not know correct time it will supress the time stamp. From the fact that the startup config does not have a time stamp we can believe that the router did not know authoritative time when the config was saved. And I do not know any good way to go back and discover it.

HTH

Rick