Does not protect against DST changes / clock going backwards

[RobThree]

When clock goes back (DST change) there's a real possibility of generating duplicate ID's. Suggestion: use a strictly increasing (monotonic) time source (this one for example).

Full disclosure: I'm the developer of IdGen which is a similar project.

[rvhuang]

@RobThree does DST affect DateTime.UtcNow?

[RobThree]

No, but any corrections made by NTP for example (which Windows does by default) will affect the time (possibly several times a day) and then there's leap seconds and all kinds of other horrible messy things people "invent" to keep track of "time". Wallclock time, which DateTime.UtcNow (and DateTime.Now) is, is not usable for this kind of applications.