The following DHCP conf section for my Alphas has always worked for 
me. The server is a  DigitalServer 3305 (nee AlphaServer 800 5/500) 
running NetBSD 1.6.2_STABLE:

subnet X.X.X.X netmask X.X.X.X {
         range X.X.X.X  X.X.X.X;
         option subnet-mask X.X.X.;
         option routers X.X.X.X;
         option broadcast-address X.X.X.X;
         server-name "fs0";
         option swap-server fs0.clock.org;
         option domain-name "clock.org";
         option domain-name-servers dns.mogul.ski.way.clock.org;
         option font-servers fs0.clock.org;
         option ntp-servers ntp.ski.way.clock.org;
         option time-servers ntp.ski.way.clock.org;
         option smtp-server smtp.ski.way.clock.org;

         group {
                 use-host-decl-names on;
                 always-reply-rfc1048 on;        # SRM sucks
                 filename "netboot.alpha";
#               next-server fs0.clock.org;
                 server-name "fs0";

                 host timex.clock.org {          # DEC Alpha Personal 
Workstation 600au
                         hardware ethernet 00:00:F8:76:21:19;    # 
21143 built-in
#                       hardware ethernet 00:00:F8:1e:3c:05;    # 
21140 DE500-AA
                         fixed-address timex.clock.org;
                         option root-path "/n/root/timex";
                 }

                 host fast.clock.org {           # DEC Alpha PC164LX
                         hardware ethernet 00:00:f8:1e:3c:eb;    # DE500-AA tlp0
                         fixed-address fast.clock.org;
                         option root-path "/n/root/fast";
                 }
}

netboot.alpha is the NetBSD secondary netboot program which lives in 
the TFTP section of the file server. The kernels for these systems 
live in their NFS mountable root.

The net numbers are replaced by X.X.X.X; edit to suit.

It has been my experience that the 21143 TULIP chips are not as well 
supported by SRM, except in the latest versions; if you want to 
reliably netboot an Alpha with old SRM, you need to install a 
21140-based DEC DE500-AA (and not the DE500-XA - it doesn't speak 
Nway, so 10/100 ethernet switches can't negotiate port speed and 
duplex with it, so port speed must be manually set at the switch, and 
in SRM variables) into an available PCI slot and use that until 
you've upgraded SRM to the latest version for your hardware.

The way to tell a DE500-XA from a DE500-AA (both have the 21140 chip) 
is the FCC-ID (DE500X versus DE500A) silk screened onto printed 
circuit board (PCB), and whether there is a socket mounted on the PCB 
for a boot ROM PROM (the AA has one, the XA does not).

	Erik <fair@netbsd.org>