U.S. Time Zone Available Addresses
Eastern time zone ntp2.usno.navy.mil
tick.usno.navy.mil
tock.usno.navy.mil
ntp-s1.cise.ufl.edu
ntp.colby.edu
navobs1.oar.net
gnomon.cc.columbia.edu
tick.gatech.edu
navobs1.mit.edu
Central time zone now.cis.okstate.edu
ntp0.mcs.anl.gov
navobs1.wustl.edu
tick.uh.edu
Mountain time zone tick.usnogps.navy.mil
tock.usnogps.navy.mil
Pacific time zone montpelier.caltech.edu
bigben.cac.washington.edu
tick.ucla.edu
usno.pa-x.dec.com
Alaska time zone ntp.alaska.edu
Hawaii time zone tick.mhpcc.edu

Table 1 Use U.S. Naval Time Sources.
The U.S. Naval Observatory provides master clocks that allow you to synchronize time in your network. You can find these addresses at http://tycho.usno.navy.mil/ntp.html. Use the addresses within your time zone to set your primary time server.