Talk:Universally unique identifier
|This is the talk page for discussing improvements to the Universally unique identifier article.
This is not a forum for general discussion of the article's subject.
|This article is of interest to the following WikiProjects:|
|The contents of the Globally unique identifier page were merged into Universally unique identifier on 16 January 2017. For the contribution history and old versions of the redirected page, please see ; for the discussion at that location, see its talk page.|
|This talk page is automatically archived by Lowercase sigmabot III. Any threads with no replies in 30 days may be automatically moved. Sections without timestamps are not archived.|
In the FORMAT section there is an example specifically labeled as Microsoft GUID. It does not specify what they mean by "Microsoft" GUID but MS does have their own GUID variant, according to https://tools.ietf.org/html/rfc4122#section-4.4. The GUID provided as an example, in the variant section starts with 'A' hex digit but Microsoft GUIDs start with C/D hex digits. Therefore that part of the format is ambiguous at lowest and incorrect at best. — Preceding unsigned comment added by Kein (talk • contribs) 16:56, 13 January 2020 (UTC)
MAC and clock - bad ideas?
It is common to copy MAC addresses over from one NIC to another in clustered environments. So make sure to use the factory MAC and not the MAC visible on the network.
The clock may generate (improbable) duplicates if it is set backwards. I already had to adjust the clock of a server backwards, probably due to a HW glitch. A rogue NTP server might be used as an attack vector.
Version 1 and 2 also have poor entropy. This is not necessarily a disadvantage. A more or less sequential nature of UUIDs may be a wanted feature .
The clock has the advantage to allow to reconstitute roughly in which order the UUIDs have been generated - if you can trust the clock.
BTW, version 6 is on the way: 
UUID generator: why only uuidgen.org allowed?
While this generator is recommended by ITU-T, I don't see uuidgen.org being recommended by any authorities (ITU-T, ISO, IETF). Only thing in that website is "@Accelery", which is a twitter account with only one tweet: "Online UUID generators seem stuck in the past, so we made a new one." That's it, no more information is given. Very flimsy. How can we trust that? How superior is that from the one recommended by ITU-T? Any users of that tool can comment? There was a comment
<!--Do not add any more GUID generator web sites; they will be removed. which discouraged editors to add alternative UUID generators. That's advertising, in my opinion. Therefore I removed it and replaced by the ITU-T one. Feelthhis (talk) 04:00, 19 December 2020 (UTC)