Short domains are useful for security testing. If you only have a limited number of characters, you need to be able to reference code on a remote server in as few characters as possible. A few years ago, I tried to find a Minimum Viable XSS. The conclusion that I (and others) came to is that 20 characters is the bare minimum. But it requires you have a 2 character domain name on a 2-character TLD. Something like xy.uk I don't think any 1- or 2-character domain names are available. If they're…