To setup a Synology NAS as a secondary DNS to provide a fall back if/when the primary DNS is off line. To setup a DNS and DHCP serve see my post for DNS with bind9 and DHCP on Ubuntu 14.04.
Updated for Ubuntu 14.04-3 LTS. If you are a home user and your network has grown such that you are tired of using all static IP addresses and having to configure the /etc/hosts files by hand, then use the great tool dnsmasq. See my How to set up dnsmasq. Dnsmasq is so much simpler to setup and maintain than bind9.