A while ago I came across a situation like this but with a tracert command
There is a special class of addresses initially allocated to Miltary in various coutries.
These addresses were not reachable for the large public (I can't remember why) and I vaguely remember that some ISPs either took the liberty or were authorize to use these classes as private addresses
In your case the OS might have been compiled in such environment of for such environment (Miltary) ...
just a crazy hpotesis .. nothing more
Suggestion: do some reasearch on that block of addresses and see who is the owner...