solara #> dig @8.8.8.8 public.p-knowledge.co.jp public.p-knowledge.co.jp. 20466 IN A 192.168.125.3
Indeed, it looks like their name servers are messed up. public.p-knowledge.co.jp. resolves to (the perfectly fine) 116.58.185.3 from ns1.p-knowledge.co.jp, but the unusable 192.168.* from ns2.p-knowledge.co.jp. (Those are their name servers listed in whois.) Sometimes the 192.168 creeps into the cache earlier and then nothing resolves. I'll disable it and see if I can reach someone responsible for it. Thanks for the report. -k