I never had a problem remembering such domains, because I found them logical. In fact, in 1996, I registered such a domain that was <street address>.<city>.<state>.us. I figured this was the most accessible one for all four of our roommates to use, and there was no cost at the time.
Come to find out that the k12.ca.us. domain is completely defunct! There is no SOA for it, and WHOIS indicates it's inactive. k12.ny.us. seems to be in the same condition. However, there are still k12.<state>.us. domains in other parts of these USA. If you search for them, you can find websites and email addresses under that hierarchy.
Come to find out that the k12.ca.us. domain is completely defunct! There is no SOA for it, and WHOIS indicates it's inactive. k12.ny.us. seems to be in the same condition. However, there are still k12.<state>.us. domains in other parts of these USA. If you search for them, you can find websites and email addresses under that hierarchy.