That is what I originally had the 501 configured with. All my other 330's work perfectly with pool.ntp.org, but the 501 did not, so I found the IP for a public time server and used that (I dont remember now if I used P=pool.npt.org or another one). Not sure why the 501 wasnt able to resolve pool.ntp.org to begin with. Strange.
And another thing, the time kept flashing like an alarm clock does when it loses its power until I changed this setting and got it working.