It looks like there are two options for providing network time settings to a DHCP client; option 004 and option 042. The description for 004 is "Time Server", while 042 specifies NTP. Is there a reason to use one or the other, or is it just vendor preference? If the client uses option 042, is the time offset in option 002 still used?
From a Google search, first result:
Option 004 specifies servers that provide TIME/ITP (as per RFC 868). This is not a recommended protocol/service in a Windows environment.
Option 042 specifies servers that provide NTP/SNTP (RFC 1769). This is the preferred time service in a Windows environment (assuming the absence of Active Directory which maintains the time on your behalf).