Hmm, I guess the current browsers simply don't like such domain and automatically put www. At the very least, the Google DNS gives the following:

    ai. 209.59.119.34
    cm. 195.24.205.60
    dk. 193.163.102.58
    gg. 87.117.196.80
    je. 87.117.196.80
    pn. 80.68.93.100
    tk. 217.119.57.22
    uz. 91.212.89.8
    ws. 64.70.19.33

But I agree that these domains are now out of luck, given that browsers no longer even remotely support them.