Google DNS at 010.010.010.010
It's also at 010.010.2056 or 0x8080808 or 01002004010. I made a little tool a while ago that iterates over all the options that I know of:https://lucb1e.com/randomprojects/php/funnip.php?ip=8.8.8.8The variant found by OP is apparently the very last option that my tool generates. These days, Firefox is a bit boring (okay, okay, I'll admit it's a good choice for security) and translates these at the first opportunity. Even hyperlinks are translated on hover in the 'status bar' (if we can still call it that). For mobile users, this is what it shows when you paste one of those addresses in Firefox: https://snipboard.io/kbLTso.jpg