>I think it is normal, my 1.2 and BSD/OS does it too. "(incomplete)" means
>only link info without ethernet address is available, which is fine (outgoing
>interface is computed for broadcast address).

i think so too, but if it leads to some like:
? (194.77.123.143) at (incomplete)
some.where.net (194.77.123.143) at 00:00:0a:00:90:ea
(the last being fictive maybe)
that can't be good, check 1.2 and BSD/OS for it.
i can't give you the reproducibility but it must be around.
~n