.net - How does C# generate GUIDs?

Question

How are GUIDs generated in C#?

Answer 1

There's a really good article on Raymond Chen's blog that describes how GUIDs are generated, and in particular why a substring of a guid is not guaranteed to be unique.

Basically, a a GUID is generated using a combination of:

• The MAC address of the machine used to generate the GUID (so GUIDs generated on different machines are unique unless MAC addresses are re-used)
• Timestamp (so GUIDs generated at different times on the same machine are unique)
• Extra "emergency uniquifier bits" (these are used to ensure that GUIDs generated at nearly exactly the same time on the same machine are unique)
• An identifier for the algorithm (so that GUIDs generated with a different algorithm are unique)

However, this is only 1 particular algorithm used for generating GUIDs (although I believe it's the one used by the .NET framework), and is not the one used by the .NET framework.