I have the following variables:-

$a=abc.1.0.1.0
$b=bnnn.1.0.1.1
$c=dnnnnn.1.0.2.0 ....etc........

i want to split the variable $a, $b, $c and put that value in two separate varaibles. 
for example 
$a is splitted to 
$a2 = 1.0.1.0 (always the last four digits of the string)
$a1 = abc (Rest of the String)

$b is splitted to 

$b2 = 1.0.1.1 (always the last four digits of the string)
$b1 = bnnn (Rest of the String)

i am trying to get the results with a for loop

Can anyone please help?