I am using the following regex.
/^(([0-9._]?)*([a-zA-Z._]|[a-zA-Z._][a-zA-Z0-9\-._]*[a-zA-Z0-9])\._)*([A-Za-z._]|[A-Za-z._][A-Za-z0-9\-._]*[A-Za-z0-9_])$/;
It fails for 1dsd.343.23fdf
but passes d1sd.343.23fdf
what is to be modified on the regex to allow first letter as a number.