OK, here's a few snippets from my server log files.

>Jul 16 23:36:08 bbs in.tftpd[163]: connect from sun2.cookeville.org
>Jul 16 23:36:10 bbs rpc.bootparamd: whoami got question for 192.251.251.38 
>Jul 16 23:36:10 bbs rpc.bootparamd: This is host sun2.cookeville.org 
>Jul 16 23:38:40 bbs rpc.bootparamd: Returning sun2   (none)    127.0.0.1

so it appears that it isn't feeding the sun the right address back.  My host
file appears to be right, and I'm puzzled over this one.  Never saw this
message before, not even the last time I installed for a netboot.
Here's the error message from the screen of the sun3:
---
>> NetBSD Netboot (Something about 1.2-e)
Using IP address 192.251.251.38 = C0FBFB26
boot: client addr: 192.251.251.38
netif_get: timeout;resetting.
bootparamd:  'whoami' call failed
net_open: bootparamd/whoami RPC failed
boot: netbsd: Input/output error
boot:
----

>From what I can figure, something isn't getting reported right from the
server to the client box.  I'm going to reboot and look again, and will let
the list know if I happen to see a silly mistake I've made.  Thanks for any
assistance you can offer me.