How CRM sets Timezone for new user by default

Hi,

I want to know how system sets Default time zone for new user.

I have seen I am creating a new user and my user record in CRM sets to (GMT) Coordinated Universal Time) timezone.

Now i creates new user and if i see his Time Zone in DB then it shows (GMT) Greenwich Mean Time : Dublin, Edinburgh, Lisbon, London')  time zone. I wonder as that user doesn't really change at personal setting option. But just after creation of new user i get to see timezone get sets automatically from somewhere.

I want to understand how CRM works in this case.

Please urgent threads needed.

Note: I am using CRM 2013 On-Premise

Thanks & Regards,

Mugdha Kelkar