regex - Regular Expression for Version -

i want regex version accepts format:

##.##.## 

====

but doesn't accept

00.00.00

if 00.00.00 not acceptable, can use following regex

00\.00\.(?:0[1-9]|[1-9]\d)|00\.(?:0[1-9]|[1-9]\d)\.\d{2}|(?:0[1-9]|[1-9]\d)\.\d{2}\.\d{2}