User:255.255.255.255

This IP address is the broadcast address of 0.0.0.0. It is not feasible for edits to come from this IP, but if there is, a bug is present in Wikimedia's servers and you should report it to the Wikimedia Phabricator.

If you are an admin who wishes to test blocking, please use for that instead.

For more information, please see broadcast address.