short names for remote hosts not in my network

[reader at newsguy.com]

Setup: Gentoo linux
       bind-9.3.2

Until I started running a local home network nameserver I used short
names for 2 remote hosts where I have user accounts, by listing them
in /etc/hosts:
  207.106.84.135  io.jtan.com                io       # gentoo
  207.106.84.134  callisto.jtan.com          callisto # obsd

Then at the command line I could `ssh io' and ssh would know it was
io.jtan.com.

My domain is a private home domain `local.net0'

I still have those entries in /etc/hosts but now that I'm running
bind, my system thinks `io' is a completely different machine not in
jtan.com domain at all.

So `ssh io' now tries to contact a different io.

   nslookup io
  Server:         127.0.0.1
  Address:        127.0.0.1#53
  
  Non-authoritative answer:
  Name:   io
  Address: 80.249.100.38
====================================

   nslookup io.jtan.com
  Server:         127.0.0.1
  Address:        127.0.0.1#53
  
  Non-authoritative answer:
  Name:   io.jtan.com
  Address: 207.106.84.135

The name io does not appear anywhere in my bind setup files.  So I'm
wondering why the short name is not known to be the one listed in
/etc/host?  Or why it doesn't just fail if /etc/hosts isn't coming
into play.

Is it coming from a cached lookup or what?