ifconfig bent on a Sun 4?

[David N. Blank]

Is the "netmask +" option to ifconfig broken on a Sun 4?  Here's a
dialogue that makes me think so:

(as root on a sun4 running 4.1)
*** Check that yp (NIS) netmask info is correct
everest# ypcat netmasks.byaddr
255.255.0.0
This file is automatically maintained.

*** For kicks check that /etc/netmasks on server is correct
everest# cat /etc/netmasks
# This file is automatically maintained.
# DO NOT EDIT IT UNLESS YOU KNOW WHAT YOU'RE DOING!!
# This data was taken out of YP map 'netmasks.byaddr' at Tue Jul 17 15:41:43 19
0

18.85.0.0       255.255.0.0

*** find the ethernet interface
everest# netstat -i
Name  Mtu  Net/Dest      Address        Ipkts  Ierrs Opkts  Oerrs Collis Queue
le0   1500 18.85.0.0     everest        39695   19   13871   1    203    0
lo0   1536 loopback      localhost      2275    0    2275    0    0      0

*** manually ifconfig it wrong & check result
everest# ifconfig le0 everest netmask 255.255.255.0 broadcast 18.85.255.255
everest# ifconfig le0
le0: flags=63<UP,BROADCAST,NOTRAILERS,RUNNING>
        inet 18.85.1.59 netmask ffffff00 broadcast 18.85.255.255
        ether 8:0:20:8:ee:2b

*** manually request that ifconfig do a lookup of netmask & check result
everest# ifconfig le0 everest netmask + broadcast 18.85.255.255
everest# ifconfig le0
le0: flags=63<UP,BROADCAST,NOTRAILERS,RUNNING>
        inet 18.85.1.59 netmask ffffff00 broadcast 18.85.255.255
        ether 8:0:20:8:ee:2b    ^^^^^^^^
                               oooops! that's not right!

That's the problem in a nutshell.  Did I miss something here?
      Respectfully,
         David N. Blank 
         M.I.T. Media Lab
         dnb at media-lab.media.mit.edu