I dont think this is at all possible because you can't pass on the cookie information from one domain to another. All browsers that do this, since you cannot control how someone controls their cookies on their computer (like for me I have it prompt me whenever a cookie wants to be added to my computer/browser)
If all the domains were registered to one IP address, then there shouldn't be a problem, and you could use the ip address instead of domain names.
Security issues
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