It’s probably better to have your DNS server be able to resolve ‘puppet’ to the right address, and have your DHCP server hand out the DNS information, or if you have static IP addresses, something like this.
iface eth0 inet static address 192.168.0.3 netmask 255.255.255.0 gateway 192.168.0.1 dns-search example.com dns-nameservers 192.168.0.1
But if you do want to do it via the resolv.conf file, wou will want to edit
In that file, after the header, put in your info like you would in resolv.conf
search puppetmaster.com nameserver 192.168.1.XXX
Then restart resolvconf
service resolvconf restart