4.4BSD/usr/src/sys/vax/if/ACC/conf/files.vax

For Ultrix (versions 2.0, 2.2, 3.0):

Add the following line to the file /sys/conf/files.vax:

vaxif/if_dda.c		optional dda device-driver Notbinary

For Berkeley UNIX,  add the following line to the file /sys/conf/files/vax:

vaxif/if_dda.c		optional dda device-driver