Q:

Match domain names as regular expressions

can some tell how can i write regular expression matching abc.com.ae or abc.net.af or anything  ,ae which is the last in the string is optional
this is successfull with / but not . don't know why 
^[a-z]{1,25}.[a-z]{3}$

answer
^[a-z]{1,30}\.[a-z]{3}((\.)[a-z]{2})?$

A:

The answer is: write \. instead of ., because . means “any character”.

