Changing the xn-- prefix
Shawn.Steele at microsoft.com
Thu Mar 20 19:18:31 CET 2008
I think that changing the prefix would be a really bad idea:
* Changing the domain name would break existing comparisons that rely on the punycode. (domain name xn--A wouldn't necessarily equal domain name xx--A)
* names wouldn't match in the registry either. The browser would have to try the new prefix name, then if that failed, it'd have to try the xn-- name for back compat.
* What happens when the xn-- and the new prefix names for the same machine/Unicode name point to different servers? This could happen either because the registrars messed up or they are on a subnet that didn't know better?
* Developers would have to consider 2 versions for even simple applications.
I think that these are much more serious that changing behavior for anything that is considered "bad" (for security) today. If a "bad" domain stops working we probably want it to stop working.
Our intent is to replace the IDN resolution mechanism for IE/Windows/.Net with updated tables when they become available. We would oppose anything that causes us to have multiple revisions or complex code paths for edge cases.
More information about the Idna-update