Netbsd root device not found

Hello there. I installed NetBSD yesterday on an older system to try it out. Everytime I boot, I have to enter in the root device (disk) manually wd0 which then proceeds into asking to define the dump device: [wd0b] is the default then, the sbin/init My question is where am I supposed to configure this? /etc.rc.conf? Thanks for any leads

can you post your fstab?