with 3.99.7 it worked fine to boot my diskless X-terminal, with 3.99.9 
doesn't. i've put dhcpd from 3.99.7 binaries and works fine again

my config is like that:

10.255.245.2 does run windows and works fine - winipcfg shows everything 
right.

10.255.245.5 is able to boot xterminal.bin that it turn boots 
/usr/local/Xterminals/wojtek/netbsd which starts, then does DHCP again
and then can't mount NFS root because server is 0.0.0.0

my config:

authoritative;
option domain-name "l.";
option domain-name-servers dns.l.;
default-lease-time 60000;
max-lease-time 72000;
ddns-updates off;
ddns-update-style none;

class "pxe-clients-ia32" {
match if substring (option vendor-class-identifier, 0, 20)
= "PXEClient:Arch:00000";
filename "xterminal.bin";
}

subnet 10.255.245.0 netmask 255.255.255.0 {
ddns-updates off;
option routers 10.255.245.1;
option subnet-mask 255.255.255.224;
option broadcast-address 10.255.245.31;
deny unknown-clients;
range 10.255.245.20 10.255.245.30;

  host mama.dom {
   hardware ethernet 00:0A:Cd:05:45:FB;
   fixed-address 10.255.245.2;
   option host-name "mama.dom";
  }

  host wojtek-term2.dom {
   hardware ethernet 00:50:04:ed:2a:3d;
   fixed-address 10.255.245.5;
   option host-name "wojtek-term2.dom";
   option root-path "/usr/local/Xterminals/wojtek";
  }

}