9

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?

11

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).

  • Unfortunately that site is unreadable unless your referer is from Google. – Zoredache May 12 '09 at 20:57
  • Rats! Did not realized, thank you. Link updated. – user1797 May 12 '09 at 21:05
  • Thanks. I wound up answering the last question myself. The (non windows) device that I'm concerned with will look for option 042 then 004, and will use 002 for GMT offset. – TimM May 13 '09 at 14:58
  • Updated the link, so it will go directly to the source, without the need of going to Google. – user1797 May 15 '09 at 11:20
4
  • Option 042 refers to NTP (RFC 1769)
  • Option 004 refers to TIME/ITP (RFC 868)

Source

1

The RFC 868 "time" service as specified by Option 4 is pretty much obsolete and only has 1s resolution.

Modern networks should always use NTP (Option 42).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.