all digits non-FQDN won't resolve!

[Farid Hamjavar]

bind 8.2.5 aix 4.3.3

Greetings,

This post is not about hostname syntax, as far as I know,
hostnames with all digits are valid (e.g. 123450987.foobar.org) 


We have this strange behavior on a handful of our hosts 
whose name happen to be made up of all digits.

nslookup and host and dig all behave in this
strange way:


if host is looked up in non-FQDN,  query fails and
no answer is returned. However, if in FQDN format, 
everything is OK.


So two questions:

1] Why this behavior for hosts whose name is all  digits?

2] Why this behavior can not be produced for
   other hostnames?


Thanks,
Farid 
UNM