Added Q/A from mailling list: (http://tahoe-lafs.org/pipermail/tahoe-dev/2010-October/005359.html)

[Imported from Trac: page FAQ, version 27]

FAQ.md

@@ -133,3 +133,19 @@ is 128KiB), and you only have to replace the segments that are dirtied by the wr
 N/k*128KiB or about 440KiB for the default 3-of-10 encoding.
 
 Kevan Carstensen is spending his summer implementing MDMF, thanks to the sponsorship of Google Summer Of Code. Ticket #393 is tracking this work.
+
+**Q: How can tahoe ensures that, every node id is unique ?**
+
+A: The node ID is randomly-generated, so there is no way to guarantee its uniqueness.  However, the ID is long enough that the probability of two randomly-generated IDs colliding is negligible.
+
+**Q: If upload the same file again and again, tahoe will give the same capability string. How is tahoe identifies that the client is same, when i upload files mutiple times, is it based on node id ?**
+
+A: For immutable files this is true.  The capability string is derived from two pieces of information:  The content of the file and the "convergence secret".  By default, the convergence secret is randomly generated by the node when it first starts up, then stored and re-used after that.  So the same file content uploaded from the same node will always have the same cap string.  Uploading the file from a different node with a different convergence secret would result in a different cap string -- and a second copy of the file's contents stored in the grid, though there's no way to tell that the two stored files are the same, because they're encrypted with different keys.
+
+**Q: When i stop a node and start it again, will the node have the same node id as of previous node start ?**
+
+A: Yes.  The node ID is stored in the my_nodeid file in your tahoe directory.
+
+**Q:  If i move the client node base directory to different maching and start the client there again, will the node have the same node id as of previous machine start ?**
+
+A: Yes, as long as you move that my_nodeid file.