In the example above - apple2cks.com - a grade 1 symbol indicator is used after the 2 in order to tell the reader that the c is a letter c and not the number 3. The grade 1 indicator terminates numeric mode but does not terminate grade 1 mode (which is set by the numeric indicator). In your example, that works because there are no contractions in the web address.
If you had the website 2019raceforthefunofit.com you would want the grade 1 terminator after 2019 so that you can use contractions in the remainder of the web address. The numeric indicator sets both grade 1 mode and numeric mode; the grade 1 terminator terminates both.
If you have 2000cansofspaghetti.com you would also want the grade 1 terminator. If you used the grade 1 symbol indicator after 2000, it would tell the reader that the c is not a 3, but it would not terminator grade 1 mode and, as such, the contractions in of and spaghetti could not be used - and you would want to use them.