Because the entries start with "a", Excel interprets the entire cell
and each of the cell's components as text. Even though the cells
contain numbers, Excel sorts them textually, and "103" appears before
"2" in an alpha sorted list.

If the format of your entries is alpha-#-#-# then one way to sort the
list is to write this formula for each entry in column B:
=Mid(A1,1,1)

.... and this entry in column C:
=value(mid(A1,2,len(A1))

Then sort simultaneously on columns B and C.